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Git pushed a commit to branch master
in repository ffmpeg.

commit 906e3edc704f0680b598fb7bd446f22a79713368
Author:     Michael Niedermayer <[email protected]>
AuthorDate: Tue Feb 3 22:06:24 2026 +0100
Commit:     Michael Niedermayer <[email protected]>
CommitDate: Sun Feb 15 20:16:11 2026 +0100

    swresample: Check user chlayout in swr_set_matrix()
    
    All callers in FFmpeg check this already, but it is a public
    function that can plausibly be given more channels.
    In which case out of array writes would occur
    
    This is likely a regression from when channel layouts where extended
    to support more than 64 channels
    
    Found-by: 이동준 <[email protected]>
    Signed-off-by: Michael Niedermayer <[email protected]>
---
 libswresample/rematrix.c            |  5 ++++-
 libswresample/swresample.c          | 28 ++++++++++++++++------------
 libswresample/swresample_internal.h |  1 +
 3 files changed, 21 insertions(+), 13 deletions(-)

diff --git a/libswresample/rematrix.c b/libswresample/rematrix.c
index b725159730..a4911a2922 100644
--- a/libswresample/rematrix.c
+++ b/libswresample/rematrix.c
@@ -66,7 +66,10 @@ int swr_set_matrix(struct SwrContext *s, const double 
*matrix, int stride)
 {
     int nb_in, nb_out, in, out;
 
-    if (!s || s->in_convert) // s needs to be allocated but not initialized
+    if (!s || s->in_convert ||   // s needs to be allocated but not initialized
+        swri_check_chlayout(s, &s->user_in_chlayout , "input") ||
+        swri_check_chlayout(s, &s->user_out_chlayout, "output")
+    )
         return AVERROR(EINVAL);
     memset(s->matrix, 0, sizeof(s->matrix));
 
diff --git a/libswresample/swresample.c b/libswresample/swresample.c
index e7ce4a10aa..1a9d644e97 100644
--- a/libswresample/swresample.c
+++ b/libswresample/swresample.c
@@ -30,6 +30,20 @@
 
 #define ALIGN 32
 
+int swri_check_chlayout(struct SwrContext *s, const AVChannelLayout *chl, 
const char *name) {
+    char l1[1024];
+    int ret;
+
+    if (!(ret = av_channel_layout_check(chl)) || chl->nb_channels > 
SWR_CH_MAX) {
+        if (ret)
+            av_channel_layout_describe(chl, l1, sizeof(l1));
+        av_log(s, AV_LOG_WARNING, "%s channel layout \"%s\" is invalid or 
unsupported.\n", name, ret ? l1 : "");
+        return AVERROR(EINVAL);
+    }
+
+    return 0;
+}
+
 int swr_set_channel_mapping(struct SwrContext *s, const int *channel_map){
     if(!s || s->in_convert) // s needs to be allocated but not initialized
         return AVERROR(EINVAL);
@@ -162,19 +176,9 @@ av_cold int swr_init(struct SwrContext *s){
     s->out.ch_count  = s-> user_out_chlayout.nb_channels;
     s-> in.ch_count  = s->  user_in_chlayout.nb_channels;
 
-    if (!(ret = av_channel_layout_check(&s->user_in_chlayout)) || 
s->user_in_chlayout.nb_channels > SWR_CH_MAX) {
-        if (ret)
-            av_channel_layout_describe(&s->user_in_chlayout, l1, sizeof(l1));
-        av_log(s, AV_LOG_WARNING, "Input channel layout \"%s\" is invalid or 
unsupported.\n", ret ? l1 : "");
+    if (swri_check_chlayout(s, &s->user_in_chlayout , "input") ||
+        swri_check_chlayout(s, &s->user_out_chlayout, "output"))
         return AVERROR(EINVAL);
-    }
-
-    if (!(ret = av_channel_layout_check(&s->user_out_chlayout)) || 
s->user_out_chlayout.nb_channels > SWR_CH_MAX) {
-        if (ret)
-            av_channel_layout_describe(&s->user_out_chlayout, l2, sizeof(l2));
-        av_log(s, AV_LOG_WARNING, "Output channel layout \"%s\" is invalid or 
unsupported.\n", ret ? l2 : "");
-        return AVERROR(EINVAL);
-    }
 
     ret  = av_channel_layout_copy(&s->in_ch_layout, &s->user_in_chlayout);
     ret |= av_channel_layout_copy(&s->out_ch_layout, &s->user_out_chlayout);
diff --git a/libswresample/swresample_internal.h 
b/libswresample/swresample_internal.h
index b016ba3315..ca2e0d7534 100644
--- a/libswresample/swresample_internal.h
+++ b/libswresample/swresample_internal.h
@@ -198,6 +198,7 @@ struct SwrContext {
 
 av_warn_unused_result
 int swri_realloc_audio(AudioData *a, int count);
+int swri_check_chlayout(struct SwrContext *s, const AVChannelLayout *chl, 
const char *name);
 
 void swri_noise_shaping_int16 (SwrContext *s, AudioData *dsts, const AudioData 
*srcs, const AudioData *noises, int count);
 void swri_noise_shaping_int32 (SwrContext *s, AudioData *dsts, const AudioData 
*srcs, const AudioData *noises, int count);

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