On Mon, Nov 20, 2017 at 12:34 PM, Michael Niedermayer <
mich...@niedermayer.cc> wrote:
> On Mon, Nov 20, 2017 at 12:01:11PM -0800, Dale Curtis wrote:
> > Derp, that's the wrong comment for this; I meant that for another thread.
> > Returning an error for optional user data seems a bit harsh, but if
> that's
> > what you want, I'm happy to change it. Please let me know if this is the
> > route you want to take.
>
> it could print a warning and continue
> but there should be something, the build/version is used to do bug
> workarounds. If that is done incorrectly it can lead to decoding issues
>
Printing a warning sounds good to me. Done.
- dale
From 2f0ae7719d20addeac4a8297a64eb57f8df9cdfd Mon Sep 17 00:00:00 2001
From: Dale Curtis <dalecur...@chromium.org>
Date: Fri, 17 Nov 2017 16:05:30 -0800
Subject: [PATCH] [mpeg4video] Fix undefined shift on assumed 8-bit input.
decode_user_data() attempts to create an integer |build|
value with 8 bits of spacing for 3 components. However
each component is an int32_t, so shifting each component
is undefined for values outside of the 8 bit range.
This patch simply clamps input to 8-bits per component
and prints out a warning that the values were clamped.
Signed-off-by: Dale Curtis <dalecur...@chromium.org>
---
libavcodec/mpeg4videodec.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/libavcodec/mpeg4videodec.c b/libavcodec/mpeg4videodec.c
index 76247c3b8c..11d4e08986 100644
--- a/libavcodec/mpeg4videodec.c
+++ b/libavcodec/mpeg4videodec.c
@@ -2153,8 +2153,15 @@ static int decode_user_data(Mpeg4DecContext *ctx, GetBitContext *gb)
e = sscanf(buf, "FFmpeg v%d.%d.%d / libavcodec build: %d", &ver, &ver2, &ver3, &build);
if (e != 4) {
e = sscanf(buf, "Lavc%d.%d.%d", &ver, &ver2, &ver3) + 1;
- if (e > 1)
- build = (ver << 16) + (ver2 << 8) + ver3;
+ if (e > 1) {
+ if (ver > 0xFF || ver2 > 0xFF || ver3 > 0xFF) {
+ av_log(s->avctx, AV_LOG_WARNING,
+ "Unknown Lavc version string encountered, %d.%d.%d; "
+ "clamping sub-version values to 8-bits.\n",
+ ver, ver2, ver3);
+ }
+ build = ((ver & 0xFF) << 16) + ((ver2 & 0xFF) << 8) + (ver3 & 0xFF);
+ }
}
if (e != 4) {
if (strcmp(buf, "ffmpeg") == 0)
--
2.15.0.448.gf294e3d99a-goog
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