From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Sat, 8 Nov 2014 17:16:41 +0000 (-0500)
Subject: Fix: off-by-one in sequence filter comparator
X-Git-Tag: v2.6.0-rc3~8
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=35c7fa927fef4a851f5a22b78b7fe883789f2a5d;p=lttng-ust.git

Fix: off-by-one in sequence filter comparator

If we pass the following sequence as event input:
- field name "seqfield2"
- seq. len.: 4
- sequence array: "testA" (5 characters),

The following filters do not have the intended effect:
* 'seqfield2=="testA"'
  - expected: no match.
  - actual behavior: match.

* 'seqfield2=="test"'
  - expected: match.
  - actual behavior: no match.

This is caused by an off-by-one in the comparison with sequence length
in the filter bytecode interpreter.

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

diff --git a/liblttng-ust/lttng-filter-interpreter.c b/liblttng-ust/lttng-filter-interpreter.c
index 29bcaeff..df4add22 100644
--- a/liblttng-ust/lttng-filter-interpreter.c
+++ b/liblttng-ust/lttng-filter-interpreter.c
@@ -58,8 +58,8 @@ int stack_strcmp(struct estack *stack, int top, const char *cmp_type)
 	for (;;) {
 		int escaped_r0 = 0;
 
-		if (unlikely(p - estack_bx(stack, top)->u.s.str > estack_bx(stack, top)->u.s.seq_len || *p == '\0')) {
-			if (q - estack_ax(stack, top)->u.s.str > estack_ax(stack, top)->u.s.seq_len || *q == '\0') {
+		if (unlikely(p - estack_bx(stack, top)->u.s.str >= estack_bx(stack, top)->u.s.seq_len || *p == '\0')) {
+			if (q - estack_ax(stack, top)->u.s.str >= estack_ax(stack, top)->u.s.seq_len || *q == '\0') {
 				return 0;
 			} else {
 				if (estack_ax(stack, top)->u.s.literal) {
@@ -70,8 +70,8 @@ int stack_strcmp(struct estack *stack, int top, const char *cmp_type)
 				return -1;
 			}
 		}
-		if (unlikely(q - estack_ax(stack, top)->u.s.str > estack_ax(stack, top)->u.s.seq_len || *q == '\0')) {
-			if (p - estack_bx(stack, top)->u.s.str > estack_bx(stack, top)->u.s.seq_len || *p == '\0') {
+		if (unlikely(q - estack_ax(stack, top)->u.s.str >= estack_ax(stack, top)->u.s.seq_len || *q == '\0')) {
+			if (p - estack_bx(stack, top)->u.s.str >= estack_bx(stack, top)->u.s.seq_len || *p == '\0') {
 				return 0;
 			} else {
 				if (estack_bx(stack, top)->u.s.literal) {