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[FFmpeg-devel,1/2] avcodec/h264_parser: Fix undefined left shift

Message ID 20200529161755.9904-1-andreas.rheinhardt@gmail.com
State New
Headers show
Series [FFmpeg-devel,1/2] avcodec/h264_parser: Fix undefined left shift
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Commit Message

Andreas Rheinhardt May 29, 2020, 4:17 p.m. UTC
Use an uint32_t for the NAL unit size of an AVC H.264 NAL unit instead
of an int as a left shift of a signed value is undefined behaviour
if the result doesn't fit into the target type.

Also make the log message never output negative lengths.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
---
 libavcodec/h264_parser.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

Comments

Michael Niedermayer May 29, 2020, 8:39 p.m. UTC | #1
On Fri, May 29, 2020 at 06:17:54PM +0200, Andreas Rheinhardt wrote:
> Use an uint32_t for the NAL unit size of an AVC H.264 NAL unit instead
> of an int as a left shift of a signed value is undefined behaviour
> if the result doesn't fit into the target type.
> 
> Also make the log message never output negative lengths.
> 
> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
> ---
>  libavcodec/h264_parser.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)

probably ok

thx

[...]
diff mbox series

Patch

diff --git a/libavcodec/h264_parser.c b/libavcodec/h264_parser.c
index d9249e578d..1d2ce3870c 100644
--- a/libavcodec/h264_parser.c
+++ b/libavcodec/h264_parser.c
@@ -84,12 +84,13 @@  static int h264_find_frame_end(H264ParseContext *p, const uint8_t *buf,
 
     for (i = 0; i < buf_size; i++) {
         if (i >= next_avc) {
-            int nalsize = 0;
+            uint32_t nalsize = 0;
             i = next_avc;
             for (j = 0; j < p->nal_length_size; j++)
                 nalsize = (nalsize << 8) | buf[i++];
-            if (nalsize <= 0 || nalsize > buf_size - i) {
-                av_log(logctx, AV_LOG_ERROR, "AVC-parser: nal size %d remaining %d\n", nalsize, buf_size - i);
+            if (!nalsize || nalsize > buf_size - i) {
+                av_log(logctx, AV_LOG_ERROR, "AVC-parser: nal size %"PRIu32" "
+                       "remaining %d\n", nalsize, buf_size - i);
                 return buf_size;
             }
             next_avc = i + nalsize;