liblttng-ust-ctl: Implement SIGBUS handling

There is an issue with the security model of lib ring buffer (lttng-ust)
vs SIGBUS handling by consumer daemon. We do not handle SIGBUS in the
consumer daemon. An application using ftruncate on a ring buffer shm
could cause the consumer to be killed with SIGBUS.

Expose the relevant APIs to allow consumer daemon to handle SIGBUS.

It requires the user application (consumerd) to define the TLS sigbus
state with DEFINE_LTTNG_UST_SIGBUS_STATE(), and to invoke
lttng_ust_ctl_sigbus_handle() when a SIGBUS is received, passing the
address causing the SIGBUS (siginfo->si_addr) as parameter.

Internally, liblttng-ust-ctl uses sigsetjmp and siglongjmp to recover
from SIGBUS, and track all accesses to shared memory ranges within the
library.

This modifies the API of liblttng-ust-ctl, and requires the user
application to define the TLS sigbus state with
DEFINE_LTTNG_UST_SIGBUS_STATE(). It therefore needs to be introduced in
locked-step between lttng-ust and lttng-tools.

It requires a major version bump of liblttng-ust-ctl soname.

Fixes: #1284
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I7ade988e3e68a87930fbcee3e14e59c3fb66e755

diff --git a/include/Makefile.am b/include/Makefile.am
index 83030c5cc3b24471ab98d2902474505f71c14f79..b1f5dce9dc27a4d3d6b57d0c557379f4bdac44df 100644 (file)
--- a/include/Makefile.am
+++ b/include/Makefile.am
@@ -37,7 +37,8 @@ nobase_include_HEADERS = \
        lttng/urcu/pointer.h \
        lttng/urcu/urcu-ust.h \
        lttng/urcu/static/pointer.h \
-       lttng/urcu/static/urcu-ust.h
+       lttng/urcu/static/urcu-ust.h \
+       lttng/ust-sigbus.h
 
 # Auto-generated by configure.
 nobase_nodist_include_HEADERS = \

diff --git a/include/lttng/ust-ctl.h b/include/lttng/ust-ctl.h
index ed944e97b0a872b657ad8ec1045c6b5c912271db..d7ab7afd1594effb4ca4d045493bc0ef9ad4ce58 100644 (file)
--- a/include/lttng/ust-ctl.h
+++ b/include/lttng/ust-ctl.h
@@ -16,6 +16,7 @@
 
 #include <lttng/ust-abi.h>
 #include <lttng/ust-utils.h>
+#include <lttng/ust-sigbus.h>
 
 #ifndef LTTNG_UST_UUID_LEN
 #define LTTNG_UST_UUID_LEN     16
@@ -251,9 +252,9 @@ int lttng_ust_ctl_get_subbuf(struct lttng_ust_ctl_consumer_stream *stream,
                unsigned long *pos);
 int lttng_ust_ctl_put_subbuf(struct lttng_ust_ctl_consumer_stream *stream);
 
-void lttng_ust_ctl_flush_buffer(struct lttng_ust_ctl_consumer_stream *stream,
+int lttng_ust_ctl_flush_buffer(struct lttng_ust_ctl_consumer_stream *stream,
                int producer_active);
-void lttng_ust_ctl_clear_buffer(struct lttng_ust_ctl_consumer_stream *stream);
+int lttng_ust_ctl_clear_buffer(struct lttng_ust_ctl_consumer_stream *stream);
 
 /* index */
 
@@ -653,4 +654,6 @@ int lttng_ust_ctl_counter_aggregate(struct lttng_ust_ctl_daemon_counter *counter
 int lttng_ust_ctl_counter_clear(struct lttng_ust_ctl_daemon_counter *counter,
                const size_t *dimension_indexes);
 
+void lttng_ust_ctl_sigbus_handle(void *addr);
+
 #endif /* _LTTNG_UST_CTL_H */

diff --git a/include/lttng/ust-sigbus.h b/include/lttng/ust-sigbus.h
new file mode 100644 (file)
index 0000000..7cdc1c1
--- /dev/null
+++ b/include/lttng/ust-sigbus.h
@@ -0,0 +1,49 @@
+/*
+ * Copyright (C) 2020 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License only.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef _LTTNG_UST_SIGBUS_H
+#define _LTTNG_UST_SIGBUS_H
+
+#include <urcu/list.h>
+#include <setjmp.h>
+
+struct lttng_ust_sigbus_range {
+       void *start;    /* inclusive */
+       void *end;      /* exclusive */
+       struct cds_list_head node;
+};
+
+struct lttng_ust_sigbus_state {
+       int jmp_ready;
+       struct cds_list_head head;      /* struct lttng_ust_sigbus_range */
+       sigjmp_buf sj_env;
+};
+
+/*
+ * Define the lttng_ust_sigbus_state TLS variable as initial-exec model
+ * to allow using it from the SIGBUS signal handler. This variable must
+ * be defined by the executable using DEFINE_LTTNG_UST_SIGBUS_STATE()
+ * rather than internally within liblttng-ust-ctl.so to ensure we don't
+ * contribute to reach glibc limits of pre-allocated TLS IE model space
+ * for shared objects.
+ */
+#define DEFINE_LTTNG_UST_SIGBUS_STATE()        \
+       __thread __attribute__((tls_model("initial-exec"))) struct lttng_ust_sigbus_state lttng_ust_sigbus_state
+
+extern __thread __attribute__((tls_model("initial-exec"))) struct lttng_ust_sigbus_state lttng_ust_sigbus_state;
+
+#endif /* _LTTNG_UST_SIGBUS_H */

diff --git a/src/common/ringbuffer-clients/metadata-template.h b/src/common/ringbuffer-clients/metadata-template.h
index c6d92936fa3864c13b532aa903cd63b7d4960b86..1f0e9fe43eeed742947e86eb3b90466d5c594595 100644 (file)
--- a/src/common/ringbuffer-clients/metadata-template.h
+++ b/src/common/ringbuffer-clients/metadata-template.h
@@ -327,10 +327,11 @@ int lttng_flush_buffer(struct lttng_ust_channel_buffer *chan)
        struct lttng_ust_ring_buffer *buf;
        int shm_fd, wait_fd, wakeup_fd;
        uint64_t memory_map_size;
+       void *memory_map_addr;
 
        buf = channel_get_ring_buffer(&client_config, rb_chan,
                        0, rb_chan->handle, &shm_fd, &wait_fd, &wakeup_fd,
-                       &memory_map_size);
+                       &memory_map_size, &memory_map_addr);
        lib_ring_buffer_switch(&client_config, buf,
                        SWITCH_ACTIVE, rb_chan->handle);
        return 0;

diff --git a/src/common/ringbuffer-clients/template.h b/src/common/ringbuffer-clients/template.h
index 5a4aa9538be65b7b2dad8e4894d92e2e64c8d521..b0a5fdd7a0910d00d7f875397d6db3d1f9adb540 100644 (file)
--- a/src/common/ringbuffer-clients/template.h
+++ b/src/common/ringbuffer-clients/template.h
@@ -787,10 +787,11 @@ int lttng_flush_buffer(struct lttng_ust_channel_buffer *chan)
        for_each_channel_cpu(cpu, rb_chan) {
                int shm_fd, wait_fd, wakeup_fd;
                uint64_t memory_map_size;
+               void *memory_map_addr;
 
                buf = channel_get_ring_buffer(&client_config, rb_chan,
                                cpu, rb_chan->handle, &shm_fd, &wait_fd,
-                               &wakeup_fd, &memory_map_size);
+                               &wakeup_fd, &memory_map_size, &memory_map_addr);
                lib_ring_buffer_switch(&client_config, buf,
                                SWITCH_ACTIVE, rb_chan->handle);
        }

diff --git a/src/common/ringbuffer/frontend.h b/src/common/ringbuffer/frontend.h
index 8867418081300457fcc88e7bd4cd2cbb47c6dfb4..ed0cc7d434493acf20323f53a69f3b544e1b4679 100644 (file)
--- a/src/common/ringbuffer/frontend.h
+++ b/src/common/ringbuffer/frontend.h
@@ -81,7 +81,8 @@ extern struct lttng_ust_ring_buffer *channel_get_ring_buffer(
                                struct lttng_ust_shm_handle *handle,
                                int *shm_fd, int *wait_fd,
                                int *wakeup_fd,
-                               uint64_t *memory_map_size)
+                               uint64_t *memory_map_size,
+                               void **memory_map_addr)
        __attribute__((visibility("hidden")));
 
 extern

diff --git a/src/common/ringbuffer/ring_buffer_frontend.c b/src/common/ringbuffer/ring_buffer_frontend.c
index 62543fa2b6e63499daea3dcad231065e94b1da4e..4d06bf63140c6218c8abf7b278cd3f7b48026194 100644 (file)
--- a/src/common/ringbuffer/ring_buffer_frontend.c
+++ b/src/common/ringbuffer/ring_buffer_frontend.c
@@ -1182,7 +1182,8 @@ struct lttng_ust_ring_buffer *channel_get_ring_buffer(
                                        struct lttng_ust_shm_handle *handle,
                                        int *shm_fd, int *wait_fd,
                                        int *wakeup_fd,
-                                       uint64_t *memory_map_size)
+                                       uint64_t *memory_map_size,
+                                       void **memory_map_addr)
 {
        struct shm_ref *ref;
 
@@ -1198,6 +1199,7 @@ struct lttng_ust_ring_buffer *channel_get_ring_buffer(
        *wakeup_fd = shm_get_wakeup_fd(handle, ref);
        if (shm_get_shm_size(handle, ref, memory_map_size))
                return NULL;
+       *memory_map_addr = handle->table->objects[ref->index].memory_map;
        return shmp(handle, chan->backend.buf[cpu].shmp);
 }
 

diff --git a/src/lib/lttng-ust-ctl/ustctl.c b/src/lib/lttng-ust-ctl/ustctl.c
index 4631a1e004315a054d952751b63f7f31d83dba55..59d2be451af7a9232ea834dc27dd9369ba45f09c 100644 (file)
--- a/src/lib/lttng-ust-ctl/ustctl.c
+++ b/src/lib/lttng-ust-ctl/ustctl.c
@@ -17,6 +17,8 @@
 #include <lttng/ust-abi.h>
 #include <lttng/ust-endian.h>
 #include <lttng/ust-common.h>
+#include <lttng/ust-sigbus.h>
+#include <urcu/rculist.h>
 
 #include "common/logging.h"
 #include "common/ustcomm.h"
@@ -62,6 +64,7 @@ struct lttng_ust_ctl_consumer_stream {
        int shm_fd, wait_fd, wakeup_fd;
        int cpu;
        uint64_t memory_map_size;
+       void *memory_map_addr;
 };
 
 #define LTTNG_UST_CTL_COUNTER_ATTR_DIMENSION_MAX 8
@@ -83,6 +86,67 @@ struct lttng_ust_ctl_daemon_counter {
        struct lttng_ust_ctl_counter_attr *attr;        /* initial attributes */
 };
 
+/*
+ * Evaluates to false if transaction begins, true if it has failed due to SIGBUS.
+ * The entire transaction must complete before the current function returns.
+ * A transaction can contain 0 or more tracked ranges as sigbus begin/end pairs.
+ */
+#define sigbus_begin() \
+({ \
+       assert(!lttng_ust_sigbus_state.jmp_ready); \
+       if (!lttng_ust_sigbus_state.head.next) { \
+               /* \
+                * Lazy init because static list initialisation is \
+                * problematic for TLS variable. \
+                */ \
+               CDS_INIT_LIST_HEAD(&lttng_ust_sigbus_state.head); \
+       } \
+       if (sigsetjmp(lttng_ust_sigbus_state.sj_env, 1)) { \
+               /* SIGBUS. */ \
+               CMM_STORE_SHARED(lttng_ust_sigbus_state.jmp_ready, 0); \
+               true; \
+       } \
+       cmm_barrier(); \
+       CMM_STORE_SHARED(lttng_ust_sigbus_state.jmp_ready, 1); \
+       false; \
+})
+
+static void sigbus_end(void)
+{
+       assert(lttng_ust_sigbus_state.jmp_ready);
+       cmm_barrier();
+       CMM_STORE_SHARED(lttng_ust_sigbus_state.jmp_ready, 0);
+}
+
+static
+void lttng_ust_sigbus_add_range(struct lttng_ust_sigbus_range *range, void *start, size_t len)
+{
+       range->start = start;
+       range->end = (char *)start + len;
+       cds_list_add_rcu(&range->node, &lttng_ust_sigbus_state.head);
+       cmm_barrier();
+}
+
+static
+void lttng_ust_sigbus_del_range(struct lttng_ust_sigbus_range *range)
+{
+       cmm_barrier();
+       cds_list_del_rcu(&range->node);
+}
+
+void lttng_ust_ctl_sigbus_handle(void *addr)
+{
+       struct lttng_ust_sigbus_range *range;
+
+       if (!CMM_LOAD_SHARED(lttng_ust_sigbus_state.jmp_ready))
+               return;
+       cds_list_for_each_entry_rcu(range, &lttng_ust_sigbus_state.head, node) {
+               if (addr < range->start || addr >= range->end)
+                       continue;
+               siglongjmp(lttng_ust_sigbus_state.sj_env, 1);
+       }
+}
+
 int lttng_ust_ctl_release_handle(int sock, int handle)
 {
        struct ustcomm_ust_msg lum;
@@ -1446,6 +1510,7 @@ struct lttng_ust_ctl_consumer_stream *
        struct lttng_ust_ring_buffer_channel *rb_chan;
        int shm_fd, wait_fd, wakeup_fd;
        uint64_t memory_map_size;
+       void *memory_map_addr;
        struct lttng_ust_ring_buffer *buf;
        int ret;
 
@@ -1458,7 +1523,7 @@ struct lttng_ust_ctl_consumer_stream *
 
        buf = channel_get_ring_buffer(&rb_chan->backend.config,
                rb_chan, cpu, handle, &shm_fd, &wait_fd,
-               &wakeup_fd, &memory_map_size);
+               &wakeup_fd, &memory_map_size, &memory_map_addr);
        if (!buf)
                return NULL;
        ret = lib_ring_buffer_open_read(buf, handle);
@@ -1474,6 +1539,7 @@ struct lttng_ust_ctl_consumer_stream *
        stream->wait_fd = wait_fd;
        stream->wakeup_fd = wakeup_fd;
        stream->memory_map_size = memory_map_size;
+       stream->memory_map_addr = memory_map_addr;
        stream->cpu = cpu;
        return stream;
 
@@ -1541,12 +1607,21 @@ void *lttng_ust_ctl_get_mmap_base(struct lttng_ust_ctl_consumer_stream *stream)
 {
        struct lttng_ust_ring_buffer *buf;
        struct lttng_ust_ctl_consumer_channel *consumer_chan;
+       struct lttng_ust_sigbus_range range;
+       void *p;
 
        if (!stream)
                return NULL;
        buf = stream->buf;
        consumer_chan = stream->chan;
-       return shmp(consumer_chan->chan->priv->rb_chan->handle, buf->backend.memory_map);
+       if (sigbus_begin())
+               return NULL;
+       lttng_ust_sigbus_add_range(&range, stream->memory_map_addr,
+                               stream->memory_map_size);
+       p = shmp(consumer_chan->chan->priv->rb_chan->handle, buf->backend.memory_map);
+       lttng_ust_sigbus_del_range(&range);
+       sigbus_end();
+       return p;       /* Users of this pointer should check for sigbus. */
 }
 
 /* returns the length to mmap. */
@@ -1602,6 +1677,8 @@ int lttng_ust_ctl_get_mmap_read_offset(struct lttng_ust_ctl_consumer_stream *str
        struct lttng_ust_ctl_consumer_channel *consumer_chan;
        struct lttng_ust_ring_buffer_backend_pages_shmp *barray_idx;
        struct lttng_ust_ring_buffer_backend_pages *pages;
+       struct lttng_ust_sigbus_range range;
+       int ret;
 
        if (!stream)
                return -EINVAL;
@@ -1610,17 +1687,31 @@ int lttng_ust_ctl_get_mmap_read_offset(struct lttng_ust_ctl_consumer_stream *str
        rb_chan = consumer_chan->chan->priv->rb_chan;
        if (rb_chan->backend.config.output != RING_BUFFER_MMAP)
                return -EINVAL;
+
+       if (sigbus_begin())
+               return -EIO;
+       ret = 0;
+       lttng_ust_sigbus_add_range(&range, stream->memory_map_addr,
+                               stream->memory_map_size);
+
        sb_bindex = subbuffer_id_get_index(&rb_chan->backend.config,
                                        buf->backend.buf_rsb.id);
        barray_idx = shmp_index(rb_chan->handle, buf->backend.array,
                        sb_bindex);
-       if (!barray_idx)
-               return -EINVAL;
+       if (!barray_idx) {
+               ret = -EINVAL;
+               goto end;
+       }
        pages = shmp(rb_chan->handle, barray_idx->shmp);
-       if (!pages)
-               return -EINVAL;
+       if (!pages) {
+               ret = -EINVAL;
+               goto end;
+       }
        *off = pages->mmap_offset;
-       return 0;
+end:
+       lttng_ust_sigbus_del_range(&range);
+       sigbus_end();
+       return ret;
 }
 
 /* returns the size of the current sub-buffer, without padding (for mmap). */
@@ -1630,6 +1721,7 @@ int lttng_ust_ctl_get_subbuf_size(struct lttng_ust_ctl_consumer_stream *stream,
        struct lttng_ust_ctl_consumer_channel *consumer_chan;
        struct lttng_ust_ring_buffer_channel *rb_chan;
        struct lttng_ust_ring_buffer *buf;
+       struct lttng_ust_sigbus_range range;
 
        if (!stream)
                return -EINVAL;
@@ -1637,8 +1729,14 @@ int lttng_ust_ctl_get_subbuf_size(struct lttng_ust_ctl_consumer_stream *stream,
        buf = stream->buf;
        consumer_chan = stream->chan;
        rb_chan = consumer_chan->chan->priv->rb_chan;
+       if (sigbus_begin())
+               return -EIO;
+       lttng_ust_sigbus_add_range(&range, stream->memory_map_addr,
+                               stream->memory_map_size);
        *len = lib_ring_buffer_get_read_data_size(&rb_chan->backend.config, buf,
                rb_chan->handle);
+       lttng_ust_sigbus_del_range(&range);
+       sigbus_end();
        return 0;
 }
 
@@ -1649,15 +1747,22 @@ int lttng_ust_ctl_get_padded_subbuf_size(struct lttng_ust_ctl_consumer_stream *s
        struct lttng_ust_ctl_consumer_channel *consumer_chan;
        struct lttng_ust_ring_buffer_channel *rb_chan;
        struct lttng_ust_ring_buffer *buf;
+       struct lttng_ust_sigbus_range range;
 
        if (!stream)
                return -EINVAL;
        buf = stream->buf;
        consumer_chan = stream->chan;
        rb_chan = consumer_chan->chan->priv->rb_chan;
+       if (sigbus_begin())
+               return -EIO;
+       lttng_ust_sigbus_add_range(&range, stream->memory_map_addr,
+                               stream->memory_map_size);
        *len = lib_ring_buffer_get_read_data_size(&rb_chan->backend.config, buf,
                rb_chan->handle);
        *len = LTTNG_UST_PAGE_ALIGN(*len);
+       lttng_ust_sigbus_del_range(&range);
+       sigbus_end();
        return 0;
 }
 
@@ -1666,27 +1771,42 @@ int lttng_ust_ctl_get_next_subbuf(struct lttng_ust_ctl_consumer_stream *stream)
 {
        struct lttng_ust_ring_buffer *buf;
        struct lttng_ust_ctl_consumer_channel *consumer_chan;
+       struct lttng_ust_sigbus_range range;
+       int ret;
 
        if (!stream)
                return -EINVAL;
        buf = stream->buf;
        consumer_chan = stream->chan;
-       return lib_ring_buffer_get_next_subbuf(buf,
+       if (sigbus_begin())
+               return -EIO;
+       lttng_ust_sigbus_add_range(&range, stream->memory_map_addr,
+                               stream->memory_map_size);
+       ret = lib_ring_buffer_get_next_subbuf(buf,
                        consumer_chan->chan->priv->rb_chan->handle);
+       lttng_ust_sigbus_del_range(&range);
+       sigbus_end();
+       return ret;
 }
 
-
 /* Release exclusive sub-buffer access, move consumer forward. */
 int lttng_ust_ctl_put_next_subbuf(struct lttng_ust_ctl_consumer_stream *stream)
 {
        struct lttng_ust_ring_buffer *buf;
        struct lttng_ust_ctl_consumer_channel *consumer_chan;
+       struct lttng_ust_sigbus_range range;
 
        if (!stream)
                return -EINVAL;
        buf = stream->buf;
        consumer_chan = stream->chan;
+       if (sigbus_begin())
+               return -EIO;
+       lttng_ust_sigbus_add_range(&range, stream->memory_map_addr,
+                               stream->memory_map_size);
        lib_ring_buffer_put_next_subbuf(buf, consumer_chan->chan->priv->rb_chan->handle);
+       lttng_ust_sigbus_del_range(&range);
+       sigbus_end();
        return 0;
 }
 
@@ -1697,13 +1817,22 @@ int lttng_ust_ctl_snapshot(struct lttng_ust_ctl_consumer_stream *stream)
 {
        struct lttng_ust_ring_buffer *buf;
        struct lttng_ust_ctl_consumer_channel *consumer_chan;
+       struct lttng_ust_sigbus_range range;
+       int ret;
 
        if (!stream)
                return -EINVAL;
        buf = stream->buf;
        consumer_chan = stream->chan;
-       return lib_ring_buffer_snapshot(buf, &buf->cons_snapshot,
+       if (sigbus_begin())
+               return -EIO;
+       lttng_ust_sigbus_add_range(&range, stream->memory_map_addr,
+                               stream->memory_map_size);
+       ret = lib_ring_buffer_snapshot(buf, &buf->cons_snapshot,
                        &buf->prod_snapshot, consumer_chan->chan->priv->rb_chan->handle);
+       lttng_ust_sigbus_del_range(&range);
+       sigbus_end();
+       return ret;
 }
 
 /*
@@ -1715,14 +1844,23 @@ int lttng_ust_ctl_snapshot_sample_positions(struct lttng_ust_ctl_consumer_stream
 {
        struct lttng_ust_ring_buffer *buf;
        struct lttng_ust_ctl_consumer_channel *consumer_chan;
+       struct lttng_ust_sigbus_range range;
+       int ret;
 
        if (!stream)
                return -EINVAL;
        buf = stream->buf;
        consumer_chan = stream->chan;
-       return lib_ring_buffer_snapshot_sample_positions(buf,
+       if (sigbus_begin())
+               return -EIO;
+       lttng_ust_sigbus_add_range(&range, stream->memory_map_addr,
+                               stream->memory_map_size);
+       ret = lib_ring_buffer_snapshot_sample_positions(buf,
                        &buf->cons_snapshot, &buf->prod_snapshot,
                        consumer_chan->chan->priv->rb_chan->handle);
+       lttng_ust_sigbus_del_range(&range);
+       sigbus_end();
+       return ret;
 }
 
 /* Get the consumer position (iteration start) */
@@ -1757,13 +1895,22 @@ int lttng_ust_ctl_get_subbuf(struct lttng_ust_ctl_consumer_stream *stream,
 {
        struct lttng_ust_ring_buffer *buf;
        struct lttng_ust_ctl_consumer_channel *consumer_chan;
+       struct lttng_ust_sigbus_range range;
+       int ret;
 
        if (!stream)
                return -EINVAL;
        buf = stream->buf;
        consumer_chan = stream->chan;
-       return lib_ring_buffer_get_subbuf(buf, *pos,
+       if (sigbus_begin())
+               return -EIO;
+       lttng_ust_sigbus_add_range(&range, stream->memory_map_addr,
+                               stream->memory_map_size);
+       ret = lib_ring_buffer_get_subbuf(buf, *pos,
                        consumer_chan->chan->priv->rb_chan->handle);
+       lttng_ust_sigbus_del_range(&range);
+       sigbus_end();
+       return ret;
 }
 
 /* Release exclusive sub-buffer access */
@@ -1771,40 +1918,63 @@ int lttng_ust_ctl_put_subbuf(struct lttng_ust_ctl_consumer_stream *stream)
 {
        struct lttng_ust_ring_buffer *buf;
        struct lttng_ust_ctl_consumer_channel *consumer_chan;
+       struct lttng_ust_sigbus_range range;
 
        if (!stream)
                return -EINVAL;
        buf = stream->buf;
        consumer_chan = stream->chan;
+       if (sigbus_begin())
+               return -EIO;
+       lttng_ust_sigbus_add_range(&range, stream->memory_map_addr,
+                               stream->memory_map_size);
        lib_ring_buffer_put_subbuf(buf, consumer_chan->chan->priv->rb_chan->handle);
+       lttng_ust_sigbus_del_range(&range);
+       sigbus_end();
        return 0;
 }
 
-void lttng_ust_ctl_flush_buffer(struct lttng_ust_ctl_consumer_stream *stream,
+int lttng_ust_ctl_flush_buffer(struct lttng_ust_ctl_consumer_stream *stream,
                int producer_active)
 {
        struct lttng_ust_ring_buffer *buf;
        struct lttng_ust_ctl_consumer_channel *consumer_chan;
+       struct lttng_ust_sigbus_range range;
 
        assert(stream);
        buf = stream->buf;
        consumer_chan = stream->chan;
+       if (sigbus_begin())
+               return -EIO;
+       lttng_ust_sigbus_add_range(&range, stream->memory_map_addr,
+                               stream->memory_map_size);
        lib_ring_buffer_switch_slow(buf,
                producer_active ? SWITCH_ACTIVE : SWITCH_FLUSH,
                consumer_chan->chan->priv->rb_chan->handle);
+       lttng_ust_sigbus_del_range(&range);
+       sigbus_end();
+       return 0;
 }
 
-void lttng_ust_ctl_clear_buffer(struct lttng_ust_ctl_consumer_stream *stream)
+int lttng_ust_ctl_clear_buffer(struct lttng_ust_ctl_consumer_stream *stream)
 {
        struct lttng_ust_ring_buffer *buf;
        struct lttng_ust_ctl_consumer_channel *consumer_chan;
+       struct lttng_ust_sigbus_range range;
 
        assert(stream);
        buf = stream->buf;
        consumer_chan = stream->chan;
+       if (sigbus_begin())
+               return -EIO;
+       lttng_ust_sigbus_add_range(&range, stream->memory_map_addr,
+                               stream->memory_map_size);
        lib_ring_buffer_switch_slow(buf, SWITCH_ACTIVE,
                consumer_chan->chan->priv->rb_chan->handle);
        lib_ring_buffer_clear_reader(buf, consumer_chan->chan->priv->rb_chan->handle);
+       lttng_ust_sigbus_del_range(&range);
+       sigbus_end();
+       return 0;
 }
 
 static
@@ -1830,6 +2000,8 @@ int lttng_ust_ctl_get_timestamp_begin(struct lttng_ust_ctl_consumer_stream *stre
        struct lttng_ust_client_lib_ring_buffer_client_cb *client_cb;
        struct lttng_ust_ring_buffer_channel *chan;
        struct lttng_ust_ring_buffer *buf;
+       struct lttng_ust_sigbus_range range;
+       int ret;
 
        if (!stream || !timestamp_begin)
                return -EINVAL;
@@ -1838,7 +2010,14 @@ int lttng_ust_ctl_get_timestamp_begin(struct lttng_ust_ctl_consumer_stream *stre
        client_cb = get_client_cb(buf, chan);
        if (!client_cb)
                return -ENOSYS;
-       return client_cb->timestamp_begin(buf, chan, timestamp_begin);
+       if (sigbus_begin())
+               return -EIO;
+       lttng_ust_sigbus_add_range(&range, stream->memory_map_addr,
+                               stream->memory_map_size);
+       ret = client_cb->timestamp_begin(buf, chan, timestamp_begin);
+       lttng_ust_sigbus_del_range(&range);
+       sigbus_end();
+       return ret;
 }
 
 int lttng_ust_ctl_get_timestamp_end(struct lttng_ust_ctl_consumer_stream *stream,
@@ -1847,6 +2026,8 @@ int lttng_ust_ctl_get_timestamp_end(struct lttng_ust_ctl_consumer_stream *stream
        struct lttng_ust_client_lib_ring_buffer_client_cb *client_cb;
        struct lttng_ust_ring_buffer_channel *chan;
        struct lttng_ust_ring_buffer *buf;
+       struct lttng_ust_sigbus_range range;
+       int ret;
 
        if (!stream || !timestamp_end)
                return -EINVAL;
@@ -1855,7 +2036,14 @@ int lttng_ust_ctl_get_timestamp_end(struct lttng_ust_ctl_consumer_stream *stream
        client_cb = get_client_cb(buf, chan);
        if (!client_cb)
                return -ENOSYS;
-       return client_cb->timestamp_end(buf, chan, timestamp_end);
+       if (sigbus_begin())
+               return -EIO;
+       lttng_ust_sigbus_add_range(&range, stream->memory_map_addr,
+                               stream->memory_map_size);
+       ret = client_cb->timestamp_end(buf, chan, timestamp_end);
+       lttng_ust_sigbus_del_range(&range);
+       sigbus_end();
+       return ret;
 }
 
 int lttng_ust_ctl_get_events_discarded(struct lttng_ust_ctl_consumer_stream *stream,
@@ -1864,6 +2052,8 @@ int lttng_ust_ctl_get_events_discarded(struct lttng_ust_ctl_consumer_stream *str
        struct lttng_ust_client_lib_ring_buffer_client_cb *client_cb;
        struct lttng_ust_ring_buffer_channel *chan;
        struct lttng_ust_ring_buffer *buf;
+       struct lttng_ust_sigbus_range range;
+       int ret;
 
        if (!stream || !events_discarded)
                return -EINVAL;
@@ -1872,7 +2062,14 @@ int lttng_ust_ctl_get_events_discarded(struct lttng_ust_ctl_consumer_stream *str
        client_cb = get_client_cb(buf, chan);
        if (!client_cb)
                return -ENOSYS;
-       return client_cb->events_discarded(buf, chan, events_discarded);
+       if (sigbus_begin())
+               return -EIO;
+       lttng_ust_sigbus_add_range(&range, stream->memory_map_addr,
+                               stream->memory_map_size);
+       ret = client_cb->events_discarded(buf, chan, events_discarded);
+       lttng_ust_sigbus_del_range(&range);
+       sigbus_end();
+       return ret;
 }
 
 int lttng_ust_ctl_get_content_size(struct lttng_ust_ctl_consumer_stream *stream,
@@ -1881,6 +2078,8 @@ int lttng_ust_ctl_get_content_size(struct lttng_ust_ctl_consumer_stream *stream,
        struct lttng_ust_client_lib_ring_buffer_client_cb *client_cb;
        struct lttng_ust_ring_buffer_channel *chan;
        struct lttng_ust_ring_buffer *buf;
+       struct lttng_ust_sigbus_range range;
+       int ret;
 
        if (!stream || !content_size)
                return -EINVAL;
@@ -1889,7 +2088,14 @@ int lttng_ust_ctl_get_content_size(struct lttng_ust_ctl_consumer_stream *stream,
        client_cb = get_client_cb(buf, chan);
        if (!client_cb)
                return -ENOSYS;
-       return client_cb->content_size(buf, chan, content_size);
+       if (sigbus_begin())
+               return -EIO;
+       lttng_ust_sigbus_add_range(&range, stream->memory_map_addr,
+                               stream->memory_map_size);
+       ret = client_cb->content_size(buf, chan, content_size);
+       lttng_ust_sigbus_del_range(&range);
+       sigbus_end();
+       return ret;
 }
 
 int lttng_ust_ctl_get_packet_size(struct lttng_ust_ctl_consumer_stream *stream,
@@ -1898,6 +2104,8 @@ int lttng_ust_ctl_get_packet_size(struct lttng_ust_ctl_consumer_stream *stream,
        struct lttng_ust_client_lib_ring_buffer_client_cb *client_cb;
        struct lttng_ust_ring_buffer_channel *chan;
        struct lttng_ust_ring_buffer *buf;
+       struct lttng_ust_sigbus_range range;
+       int ret;
 
        if (!stream || !packet_size)
                return -EINVAL;
@@ -1906,7 +2114,14 @@ int lttng_ust_ctl_get_packet_size(struct lttng_ust_ctl_consumer_stream *stream,
        client_cb = get_client_cb(buf, chan);
        if (!client_cb)
                return -ENOSYS;
-       return client_cb->packet_size(buf, chan, packet_size);
+       if (sigbus_begin())
+               return -EIO;
+       lttng_ust_sigbus_add_range(&range, stream->memory_map_addr,
+                               stream->memory_map_size);
+       ret = client_cb->packet_size(buf, chan, packet_size);
+       lttng_ust_sigbus_del_range(&range);
+       sigbus_end();
+       return ret;
 }
 
 int lttng_ust_ctl_get_stream_id(struct lttng_ust_ctl_consumer_stream *stream,
@@ -1915,6 +2130,8 @@ int lttng_ust_ctl_get_stream_id(struct lttng_ust_ctl_consumer_stream *stream,
        struct lttng_ust_client_lib_ring_buffer_client_cb *client_cb;
        struct lttng_ust_ring_buffer_channel *chan;
        struct lttng_ust_ring_buffer *buf;
+       struct lttng_ust_sigbus_range range;
+       int ret;
 
        if (!stream || !stream_id)
                return -EINVAL;
@@ -1923,7 +2140,14 @@ int lttng_ust_ctl_get_stream_id(struct lttng_ust_ctl_consumer_stream *stream,
        client_cb = get_client_cb(buf, chan);
        if (!client_cb)
                return -ENOSYS;
-       return client_cb->stream_id(buf, chan, stream_id);
+       if (sigbus_begin())
+               return -EIO;
+       lttng_ust_sigbus_add_range(&range, stream->memory_map_addr,
+                               stream->memory_map_size);
+       ret = client_cb->stream_id(buf, chan, stream_id);
+       lttng_ust_sigbus_del_range(&range);
+       sigbus_end();
+       return ret;
 }
 
 int lttng_ust_ctl_get_current_timestamp(struct lttng_ust_ctl_consumer_stream *stream,
@@ -1932,6 +2156,8 @@ int lttng_ust_ctl_get_current_timestamp(struct lttng_ust_ctl_consumer_stream *st
        struct lttng_ust_client_lib_ring_buffer_client_cb *client_cb;
        struct lttng_ust_ring_buffer_channel *chan;
        struct lttng_ust_ring_buffer *buf;
+       struct lttng_ust_sigbus_range range;
+       int ret;
 
        if (!stream || !ts)
                return -EINVAL;
@@ -1940,7 +2166,14 @@ int lttng_ust_ctl_get_current_timestamp(struct lttng_ust_ctl_consumer_stream *st
        client_cb = get_client_cb(buf, chan);
        if (!client_cb || !client_cb->current_timestamp)
                return -ENOSYS;
-       return client_cb->current_timestamp(buf, chan, ts);
+       if (sigbus_begin())
+               return -EIO;
+       lttng_ust_sigbus_add_range(&range, stream->memory_map_addr,
+                               stream->memory_map_size);
+       ret = client_cb->current_timestamp(buf, chan, ts);
+       lttng_ust_sigbus_del_range(&range);
+       sigbus_end();
+       return ret;
 }
 
 int lttng_ust_ctl_get_sequence_number(struct lttng_ust_ctl_consumer_stream *stream,
@@ -1949,6 +2182,8 @@ int lttng_ust_ctl_get_sequence_number(struct lttng_ust_ctl_consumer_stream *stre
        struct lttng_ust_client_lib_ring_buffer_client_cb *client_cb;
        struct lttng_ust_ring_buffer_channel *chan;
        struct lttng_ust_ring_buffer *buf;
+       struct lttng_ust_sigbus_range range;
+       int ret;
 
        if (!stream || !seq)
                return -EINVAL;
@@ -1957,7 +2192,14 @@ int lttng_ust_ctl_get_sequence_number(struct lttng_ust_ctl_consumer_stream *stre
        client_cb = get_client_cb(buf, chan);
        if (!client_cb || !client_cb->sequence_number)
                return -ENOSYS;
-       return client_cb->sequence_number(buf, chan, seq);
+       if (sigbus_begin())
+               return -EIO;
+       lttng_ust_sigbus_add_range(&range, stream->memory_map_addr,
+                               stream->memory_map_size);
+       ret = client_cb->sequence_number(buf, chan, seq);
+       lttng_ust_sigbus_del_range(&range);
+       sigbus_end();
+       return ret;
 }
 
 int lttng_ust_ctl_get_instance_id(struct lttng_ust_ctl_consumer_stream *stream,
@@ -1966,6 +2208,8 @@ int lttng_ust_ctl_get_instance_id(struct lttng_ust_ctl_consumer_stream *stream,
        struct lttng_ust_client_lib_ring_buffer_client_cb *client_cb;
        struct lttng_ust_ring_buffer_channel *chan;
        struct lttng_ust_ring_buffer *buf;
+       struct lttng_ust_sigbus_range range;
+       int ret;
 
        if (!stream || !id)
                return -EINVAL;
@@ -1974,7 +2218,14 @@ int lttng_ust_ctl_get_instance_id(struct lttng_ust_ctl_consumer_stream *stream,
        client_cb = get_client_cb(buf, chan);
        if (!client_cb)
                return -ENOSYS;
-       return client_cb->instance_id(buf, chan, id);
+       if (sigbus_begin())
+               return -EIO;
+       lttng_ust_sigbus_add_range(&range, stream->memory_map_addr,
+                               stream->memory_map_size);
+       ret = client_cb->instance_id(buf, chan, id);
+       lttng_ust_sigbus_del_range(&range);
+       sigbus_end();
+       return ret;
 }
 
 #ifdef HAVE_LINUX_PERF_EVENT_H