On 2017-08-18 08:14, Vitaly Buka wrote:
Signed integer overflow is undefined behavior.
Detected with clang and -fsanitize=signed-integer-overflow
Signed-off-by: Vitaly Buka <vitalyb...@google.com>
---
libavcodec/utils.c | 2 +-
libavformat/aviobuf.c | 4 +++-
libavformat/mov.c | 2 +-
3 files changed, 5 insertions(+), 3 deletions(-)
diff --git a/libavcodec/utils.c b/libavcodec/utils.c
index 1336e921c9..024dc1f3e2 100644
--- a/libavcodec/utils.c
+++ b/libavcodec/utils.c
@@ -971,7 +971,7 @@ FF_ENABLE_DEPRECATION_WARNINGS
}
if (!avctx->rc_initial_buffer_occupancy)
- avctx->rc_initial_buffer_occupancy = avctx->rc_buffer_size * 3 / 4;
+ avctx->rc_initial_buffer_occupancy = avctx->rc_buffer_size * 3ll /
4;
Didn't know you could use lower case for long long constants. Neat
if (avctx->ticks_per_frame && avctx->time_base.num &&
avctx->ticks_per_frame > INT_MAX / avctx->time_base.num) {
diff --git a/libavformat/aviobuf.c b/libavformat/aviobuf.c
index 7f4e740a33..319a402faf 100644
--- a/libavformat/aviobuf.c
+++ b/libavformat/aviobuf.c
@@ -259,7 +259,9 @@ int64_t avio_seek(AVIOContext *s, int64_t offset, int
whence)
offset1 = pos + (s->buf_ptr - s->buffer);
if (offset == 0)
return offset1;
- offset += offset1;
+ // Use unsigned type to avoid undefined behavior of singed overflow.
+ // Code below will report error on overflow anyway.
+ offset += (uint64_t)offset1;
I presume offset1 is some value which is never >= 1<<63?
}
if (offset < 0)
return AVERROR(EINVAL);
diff --git a/libavformat/mov.c b/libavformat/mov.c
index 522ce60c2d..a14c9f182b 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -5572,7 +5572,7 @@ static int mov_read_default(MOVContext *c, AVIOContext
*pb, MOVAtom atom)
if (atom.size < 0)
atom.size = INT64_MAX;
- while (total_size + 8 <= atom.size && !avio_feof(pb)) {
+ while (total_size <= atom.size - 8 && !avio_feof(pb)) {
atom.size can never be < 8?
/Tomas
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