On 2/14/2021 6:36 PM, Andreas Rheinhardt wrote:
James Almer:
On 2/14/2021 6:23 PM, Andreas Rheinhardt wrote:
James Almer:
On 2/14/2021 6:09 PM, Paul B Mahol wrote:
Fixes following report:
libavformat/utils.c:1429:14: runtime error: applying zero offset to
null pointer
How is data NULL here? That's the input packet's data pointer, and this
loop is accessed only if size is > 0. data == NULL and size != 0 doesn't
sound valid. Or am i missing something?
Flushing.
A flush packet with data == NULL and size != 0? ff_read_packet(), called
before the flush attempt, initializes the packet to defaults. So if it
returns < 1, shouldn't the packet remain clean?
A flush packet with data == NULL and size == 0. And the parser of course
returns 0 in this case, which leads to NULL + 0, which is UB.
Oh, i missed the flush && got_output check that bypasses the size one.
Nevermind then.
Try compiling with assert level set to 1, see if you get an assertion
failure on avpacket helpers.
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior
libavformat/utils.c:1429:14
Signed-off-by: Paul B Mahol <one...@gmail.com>
---
libavformat/utils.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/libavformat/utils.c b/libavformat/utils.c
index 3e955b85bc..e4f100fda2 100644
--- a/libavformat/utils.c
+++ b/libavformat/utils.c
@@ -1426,8 +1426,10 @@ static int parse_packet(AVFormatContext *s,
AVPacket *pkt,
pkt->pts = pkt->dts = AV_NOPTS_VALUE;
pkt->pos = -1;
/* increment read pointer */
- data += len;
- size -= len;
+ if (len > 0) {
+ data += len;
+ size -= len;
+ }
got_output = !!out_pkt.size;
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