On 6/20/2024 7:54 PM, Michael Niedermayer wrote:
On Wed, Jun 19, 2024 at 03:08:58PM +0200, Rémi Denis-Courmont wrote:
Le 19 juin 2024 14:34:59 GMT+02:00, James Almer <jamr...@gmail.com> a écrit :
On 6/18/2024 4:07 AM, Rémi Denis-Courmont wrote:
Le 17 juin 2024 01:08:27 GMT+02:00, Michael Niedermayer
<mich...@niedermayer.cc> a écrit :
Fixes: signed integer overflow: 2314885530818453536 + 9151314442816847872
cannot be represented in type 'long'
Fixes:
68359/clusterfuzz-testcase-minimized-ffmpeg_dem_MOV_fuzzer-6571950311800832
Found-by: continuous fuzzing process
https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc>
---
libavformat/mov.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/libavformat/mov.c b/libavformat/mov.c
index 9016cd5ad08..46cbce98040 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -8131,7 +8131,9 @@ static int mov_read_iloc(MOVContext *c, AVIOContext *pb,
MOVAtom atom)
}
for (int j = 0; j < extent_count; j++) {
if (rb_size(pb, &extent_offset, offset_size) < 0 ||
- rb_size(pb, &extent_length, length_size) < 0)
+ rb_size(pb, &extent_length, length_size) < 0 ||
+ base_offset < 0 || extent_offset < 0 ||
+ base_offset + (uint64_t)extent_offset > INT64_MAX)
Can we please stop with the bespoke arithmetic overflow checks and add
dedicated helpers instead, similar to what GCC and C23 have?
You mean the __builtin_*_overflow() one?
I'd rather the ckd_*() stuff but the differences are mostly stylistic.
Whatever is used must be supported by all currently supported platforms
that especially also includes past releases we backport things to.
In practice that means continuing to use the classical way to check
as well as our av_sat_addXY() stuff.
We cannot backport things that depend on C23 as that was not a requirement
in the past. So I also cannot use this in bug fixes.
This change is ok for now (With my suggestion amended to it). We can add
wrappers around the GCC builtins and C23 ckd_* macros later (With pure C
fallbacks), and start using them for future changes.
thx
[...]
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