Invalid out or int fmts are got from the user input, which was
discovered through fuzzing. Don't know where to add check at the time of
SwrContext creating, but I think this change is redundant to at least
prevent dangerous out of bounds access, which set the pointer to illegal
address.
On 2023-08-02 13:51, Andreas Rheinhardt wrote:
kobrineli:
From: Eli Kobrin <kobrin...@ispras.ru>
We've been fuzzing torchvision with
[sydr-fuzz](https://github.com/ispras/oss-sydr-fuzz)
and found out of bounds error in ffmpeg project at audioconvert.c:51.
To prevent error we need to insert corresponding check.
Signed-off-by: Eli Kobrin <kobrin...@ispras.ru>
---
libswresample/audioconvert.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/libswresample/audioconvert.c
b/libswresample/audioconvert.c
index 1d75ba1495..701f4808a0 100644
--- a/libswresample/audioconvert.c
+++ b/libswresample/audioconvert.c
@@ -148,7 +148,12 @@ AudioConvert *swri_audio_convert_alloc(enum
AVSampleFormat out_fmt,
int flags)
{
AudioConvert *ctx;
- conv_func_type *f =
fmt_pair_to_conv_functions[av_get_packed_sample_fmt(out_fmt) +
AV_SAMPLE_FMT_NB*av_get_packed_sample_fmt(in_fmt)];
+
+ size_t idx = av_get_packed_sample_fmt(out_fmt) + AV_SAMPLE_FMT_NB
* av_get_packed_sample_fmt(in_fmt);
+ if (idx >= AV_SAMPLE_FMT_NB * AV_SAMPLE_FMT_NB)
+ return NULL;
+
+ conv_func_type *f = fmt_pair_to_conv_functions[idx];
if (!f)
return NULL;
Something seems to be using an invalid sample format (either out_fmt or
in_fmt). You should investigate where this comes from.
(Given that this is a public function, we should probably validate user
input; and maybe stop using AV_SAMPLE_FMT_NB altogether.)
- Andreas
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