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Git pushed a commit to branch release/8.1
in repository ffmpeg.

commit 08a31e67afd8dcc915994046575fba941883c428
Author:     Sankalpa Sarkar <[email protected]>
AuthorDate: Fri Mar 27 21:12:46 2026 +0530
Commit:     Michael Niedermayer <[email protected]>
CommitDate: Sun May 3 19:24:51 2026 +0200

    avformat: check avio_read() return values in dss/dtshd/mlv
    
    Multiple demuxers call avio_read() without checking its return
    value. When input is truncated, destination buffers remain
    uninitialized but are still used for offset calculations, memcmp,
    and metadata handling. This results in undefined behavior
    (detectable with Valgrind/MSan).
    
    Fix this by checking the return value of avio_read() in:
    - dss.c: dss_read_seek() — check before using header buffer
    - dtshddec.c: FILEINFO chunk — check before using value buffer
    - mlvdec.c: check_file_header() — check before memcmp on version
    
    Fixes: #21520
    (cherry picked from commit 65eed0732cadc42b3689788f175d921974f9c074)
    Signed-off-by: Michael Niedermayer <[email protected]>
---
 libavformat/dss.c      | 5 ++++-
 libavformat/dtshddec.c | 7 ++++++-
 libavformat/mlvdec.c   | 6 +++++-
 3 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/libavformat/dss.c b/libavformat/dss.c
index 6cabdb5421..ce86b32d6f 100644
--- a/libavformat/dss.c
+++ b/libavformat/dss.c
@@ -26,6 +26,7 @@
 #include "avformat.h"
 #include "demux.h"
 #include "internal.h"
+#include "avio_internal.h"
 
 #define DSS_HEAD_OFFSET_AUTHOR        0xc
 #define DSS_AUTHOR_SIZE               16
@@ -339,7 +340,9 @@ static int dss_read_seek(AVFormatContext *s, int 
stream_index,
     if (ret < 0)
         return ret;
 
-    avio_read(s->pb, header, DSS_AUDIO_BLOCK_HEADER_SIZE);
+    ret = ffio_read_size(s->pb, header, DSS_AUDIO_BLOCK_HEADER_SIZE);
+    if (ret < 0)
+        return ret;
     ctx->swap = !!(header[0] & 0x80);
     offset = 2*header[1] + 2*ctx->swap;
     if (offset < DSS_AUDIO_BLOCK_HEADER_SIZE)
diff --git a/libavformat/dtshddec.c b/libavformat/dtshddec.c
index b980fde6a9..843fd5460d 100644
--- a/libavformat/dtshddec.c
+++ b/libavformat/dtshddec.c
@@ -26,6 +26,7 @@
 #include "avformat.h"
 #include "demux.h"
 #include "internal.h"
+#include "avio_internal.h"
 
 #define AUPR_HDR 0x415550522D484452
 #define AUPRINFO 0x41555052494E464F
@@ -125,7 +126,11 @@ static int dtshd_read_header(AVFormatContext *s)
             value = av_malloc(chunk_size);
             if (!value)
                 goto skip;
-            avio_read(pb, value, chunk_size);
+            ret = ffio_read_size(pb, value, chunk_size);
+            if (ret < 0) {
+                av_free(value);
+                goto skip;
+            }
             value[chunk_size - 1] = 0;
             av_dict_set(&s->metadata, "fileinfo", value,
                         AV_DICT_DONT_STRDUP_VAL);
diff --git a/libavformat/mlvdec.c b/libavformat/mlvdec.c
index fa35bc9c45..2c1fe001c7 100644
--- a/libavformat/mlvdec.c
+++ b/libavformat/mlvdec.c
@@ -36,6 +36,7 @@
 #include "avformat.h"
 #include "demux.h"
 #include "internal.h"
+#include "avio_internal.h"
 #include "riff.h"
 
 #define MLV_VERSION "v2.0"
@@ -74,12 +75,15 @@ static int check_file_header(AVIOContext *pb, uint64_t guid)
 {
     unsigned int size;
     uint8_t version[8];
+    int ret;
 
     avio_skip(pb, 4);
     size = avio_rl32(pb);
     if (size < 52)
         return AVERROR_INVALIDDATA;
-    avio_read(pb, version, 8);
+    ret = ffio_read_size(pb, version, 8);
+    if (ret < 0)
+        return ret;
     if (memcmp(version, MLV_VERSION, 5) || avio_rl64(pb) != guid)
         return AVERROR_INVALIDDATA;
     avio_skip(pb, size - 24);

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