From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Tue, 8 Mar 2016 16:34:01 +0000 (-0500)
Subject: Fix: filter interpreter with userspace strings
X-Git-Tag: v2.7.2~1
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=e2b3f656f1a73942d345fd1a509d00bb00cf9029;p=lttng-modules.git

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 ffce2150..7c80c35c 100644
--- a/lttng-filter-interpreter.c
+++ b/lttng-filter-interpreter.c
@@ -816,7 +816,7 @@ 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");
@@ -841,7 +841,7 @@ 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)) {