From: michaelni via ffmpeg-devel <ffmpeg-devel@ffmpeg.org>
To: ffmpeg-devel@ffmpeg.org
Cc: michaelni <code@ffmpeg.org>
Subject: [FFmpeg-devel] [PATCH] avcodec/sanm: Check w,h,left,top (PR #20268)
Date: Sun, 17 Aug 2025 16:39:56 +0300 (EEST)
Message-ID: <20250817133956.DCB7768D363@ffbox0-bg.ffmpeg.org> (raw)
PR #20268 opened by michaelni
URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/20268
Patch URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/20268.patch
The setup code fow w,h,left,top is complex, the code using it also falls in
at least 2 different classes, one using left/top the other not.
To ensure no out of array access happens we add this clear check.
Fixes: out of array access
Fixes: 439261995/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_SANM_fuzzer-5383455572819968
Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
From 134fbfd1dcb59441e38d870ddd231772f4e8e127 Mon Sep 17 00:00:00 2001
From: Michael Niedermayer <michael@niedermayer.cc>
Date: Sun, 17 Aug 2025 15:31:48 +0200
Subject: [PATCH] avcodec/sanm: Check w,h,left,top
The setup code fow w,h,left,top is complex, the code using it also falls in
at least 2 different classes, one using left/top the other not.
To ensure no out of array access happens we add this clear check.
Fixes: out of array access
Fixes: 439261995/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_SANM_fuzzer-5383455572819968
Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
---
libavcodec/sanm.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/libavcodec/sanm.c b/libavcodec/sanm.c
index a066a864eb..9e99aa9dd9 100644
--- a/libavcodec/sanm.c
+++ b/libavcodec/sanm.c
@@ -1757,6 +1757,11 @@ static int process_frame_obj(SANMVideoContext *ctx, GetByteContext *gb)
memset(ctx->fbuf, 0, ctx->frm0_size);
}
+ if (w + FFMAX(left, 0) > ctx->avctx->width || h + FFMAX(top, 0) > ctx->avctx->height) {
+ avpriv_request_sample(ctx->avctx, "overly large frame\n");
+ return AVERROR_PATCHWELCOME;
+ }
+
switch (codec) {
case 1:
case 3:
--
2.49.1
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