Fix: filter interpreter with userspace strings

The filter interpreter is populating the "str" register field, but the
string comparison functions expect to use the "user_str" register field
whenever it deals with a userspace string ("user" flag set to 1).

Since we are using __copy_from_user_inatomic(), this is typically
bailing out on anything that requires to read the string (except the '*'
wildcard).

Fixes #943

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/lttng-filter-interpreter.c b/lttng-filter-interpreter.c
index c288cc024ad90bcbc58f02a849aa074632f04ec3..713a9d7d406f9f9c08c9fcb6e61f3acd43a92d8a 100644 (file)
--- a/lttng-filter-interpreter.c
+++ b/lttng-filter-interpreter.c
@@ -818,7 +818,7 @@ uint64_t lttng_filter_interpret_bytecode(void *filter_data,
                        dbg_printk("load field ref offset %u type user string\n",
                                ref->offset);
                        estack_push(stack, top, ax, bx);
-                       estack_ax(stack, top)->u.s.str =
+                       estack_ax(stack, top)->u.s.user_str =
                                *(const char * const *) &filter_stack_data[ref->offset];
                        if (unlikely(!estack_ax(stack, top)->u.s.str)) {
                                dbg_printk("Filter warning: loading a NULL string.\n");
@@ -843,7 +843,7 @@ uint64_t lttng_filter_interpret_bytecode(void *filter_data,
                        estack_push(stack, top, ax, bx);
                        estack_ax(stack, top)->u.s.seq_len =
                                *(unsigned long *) &filter_stack_data[ref->offset];
-                       estack_ax(stack, top)->u.s.str =
+                       estack_ax(stack, top)->u.s.user_str =
                                *(const char **) (&filter_stack_data[ref->offset
                                                                + sizeof(unsigned long)]);
                        if (unlikely(!estack_ax(stack, top)->u.s.str)) {