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authorAndreas Rheinhardt2019-11-17 08:34:36 +0100
committerJames Almer2019-12-31 16:57:37 -0300
commit4667920455c0d52c25835ff81098254213f2d018 (patch)
tree431dbc0a0d8c4ecdf052e06cf25c8a50d03dd809 /libavcodec
parent1cf238d3bfefdfd3345ca262f57e08a798bb0d90 (diff)
avcodec/cbs: Fix potential overflow
The number of bits in a PutBitContext must fit into an int, yet nothing guaranteed the size argument cbs_write_unit_data() uses in init_put_bits() to be in the range 0..INT_MAX / 8. This has been changed. Furthermore, the check 8 * data_size > data_bit_start that there is data beyond the initial padding when writing mpeg2 or H.264/5 slices could also overflow, so divide it by 8 to get an equivalent check without this problem. Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com> (cherry picked from commit cda3e8ca04c0e343f5b60fda8fb467936e176f33)
Diffstat (limited to 'libavcodec')
-rw-r--r--libavcodec/cbs.c4
-rw-r--r--libavcodec/cbs_h2645.c2
-rw-r--r--libavcodec/cbs_mpeg2.c2
3 files changed, 5 insertions, 3 deletions
diff --git a/libavcodec/cbs.c b/libavcodec/cbs.c
index 047f4fb898..0ce66170ec 100644
--- a/libavcodec/cbs.c
+++ b/libavcodec/cbs.c
@@ -309,7 +309,9 @@ static int cbs_write_unit_data(CodedBitstreamContext *ctx,
if (ret < 0) {
if (ret == AVERROR(ENOSPC)) {
// Overflow.
- ctx->write_buffer_size *= 2;
+ if (ctx->write_buffer_size == INT_MAX / 8)
+ return AVERROR(ENOMEM);
+ ctx->write_buffer_size = FFMIN(2 * ctx->write_buffer_size, INT_MAX / 8);
goto reallocate_and_try_again;
}
// Write failed for some other reason.
diff --git a/libavcodec/cbs_h2645.c b/libavcodec/cbs_h2645.c
index ba442b62ed..e272b0bcf6 100644
--- a/libavcodec/cbs_h2645.c
+++ b/libavcodec/cbs_h2645.c
@@ -1101,7 +1101,7 @@ static int cbs_h2645_write_slice_data(CodedBitstreamContext *ctx,
const uint8_t *pos = data + data_bit_start / 8;
av_assert0(data_bit_start >= 0 &&
- 8 * data_size > data_bit_start);
+ data_size > data_bit_start / 8);
if (data_size * 8 + 8 > put_bits_left(pbc))
return AVERROR(ENOSPC);
diff --git a/libavcodec/cbs_mpeg2.c b/libavcodec/cbs_mpeg2.c
index a49a403b26..98a22e3a68 100644
--- a/libavcodec/cbs_mpeg2.c
+++ b/libavcodec/cbs_mpeg2.c
@@ -301,7 +301,7 @@ static int cbs_mpeg2_write_slice(CodedBitstreamContext *ctx,
uint8_t *pos = slice->data + slice->data_bit_start / 8;
av_assert0(slice->data_bit_start >= 0 &&
- 8 * slice->data_size > slice->data_bit_start);
+ slice->data_size > slice->data_bit_start / 8);
if (slice->data_size * 8 + 8 > put_bits_left(pbc))
return AVERROR(ENOSPC);