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lavc: check for overflow in init_get_bits

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Fix an undefined behaviour and make the function return a proper
error in case of overflow.

CC: libav-stable@libav.org
This commit is contained in:
Luca Barbato 2013-01-13 19:52:45 +01:00
parent 90cfc084e3
commit d9cf5f5169
1 changed files with 15 additions and 7 deletions
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22
libavcodec/get_bits.h
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@ -362,20 +362,27 @@ static inline int check_marker(GetBitContext *s, const char *msg)
}
/**
* Inititalize GetBitContext.
* @param buffer bitstream buffer, must be FF_INPUT_BUFFER_PADDING_SIZE bytes larger than the actual read bits
* because some optimized bitstream readers read 32 or 64 bit at once and could read over the end
* Initialize GetBitContext.
* @param buffer bitstream buffer, must be FF_INPUT_BUFFER_PADDING_SIZE bytes
* larger than the actual read bits because some optimized bitstream
* readers read 32 or 64 bit at once and could read over the end
* @param bit_size the size of the buffer in bits
* @return 0 on success, AVERROR_INVALIDDATA if the buffer_size would overflow.
*/
static inline void init_get_bits(GetBitContext *s, const uint8_t *buffer,
int bit_size)
static inline int init_get_bits(GetBitContext *s, const uint8_t *buffer,
int bit_size)
{
int buffer_size = (bit_size+7)>>3;
if (buffer_size < 0 || bit_size < 0) {
int buffer_size;
int ret = 0;
if (bit_size > INT_MAX - 7 || bit_size <= 0) {
buffer_size = bit_size = 0;
buffer = NULL;
ret = AVERROR_INVALIDDATA;
}
buffer_size = (bit_size + 7) >> 3;
s->buffer = buffer;
s->size_in_bits = bit_size;
#if !UNCHECKED_BITSTREAM_READER
@ -383,6 +390,7 @@ static inline void init_get_bits(GetBitContext *s, const uint8_t *buffer,
#endif
s->buffer_end = buffer + buffer_size;
s->index = 0;
return ret;
}
static inline void align_get_bits(GetBitContext *s)