[FFmpeg-devel] [PATCH] avfilter/avfiltergraph: fix constant string comparision (PR #21050)

["Kacper Michajłow via ffmpeg-devel" <ffmpeg-devel@ffmpeg.org>]

PR #21050 opened by Kacper Michajłow (kasper93)
URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/21050
Patch URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/21050.patch

It's not guaranteed that the conversion filter name string will be
deduplicated to the same memory location. While this is common
optimization to do, we cannot rely on it always happening.

Fixes: 8b375b2ffd4377909180241cdc65d63d372a35a3


From bcdf9598a290cb4d9cccd05366920631dff4751b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Kacper=20Michaj=C5=82ow?= <kasper93@gmail.com>
Date: Sun, 30 Nov 2025 01:56:07 +0100
Subject: [PATCH] avfilter/avfiltergraph: fix constant string comparision
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

It's not guaranteed that the conversion filter name string will be
deduplicated to the same memory location. While this is common
optimization to do, we cannot rely on it always happening.

Fixes: 8b375b2ffd4377909180241cdc65d63d372a35a3

Signed-off-by: Kacper Michajłow <kasper93@gmail.com>
---
 libavfilter/avfiltergraph.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libavfilter/avfiltergraph.c b/libavfilter/avfiltergraph.c
index a46a7bd408..d5c2ef54e6 100644
--- a/libavfilter/avfiltergraph.c
+++ b/libavfilter/avfiltergraph.c
@@ -570,7 +570,7 @@ retry:
                 void *b = FF_FIELD_AT(void *, m->offset, link->outcfg);
                 if (a && b && a != b && !m->can_merge(a, b)) {
                     for (k = 0; k < num_conv; k++) {
-                        if (conv_filters[k] == m->conversion_filter)
+                        if (!strcmp(conv_filters[k], m->conversion_filter))
                             break;
                     }
                     if (k == num_conv) {
@@ -683,7 +683,7 @@ retry:
 
                 for (neg_step = 0; neg_step < neg->nb_mergers; neg_step++) {
                     const AVFilterFormatsMerger *m = &neg->mergers[neg_step];
-                    if (m->conversion_filter != conv_filters[k])
+                    if (strcmp(m->conversion_filter, conv_filters[k]))
                         continue;
                     if ((ret = MERGE(m,  inlink)) <= 0 ||
                         (ret = MERGE(m, outlink)) <= 0) {
-- 
2.49.1

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