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rtmp: fix buffer overflows in ff_amf_tag_contents() 

A negative `size' will bypass FFMIN().  In the subsequent memcpy() call,
`size' will be considered as a large positive value, leading to a buffer
overflow.

Change the type of `size' to unsigned int to avoid buffer overflow, and
simplify overflow checks accordingly. Also change a literal buffer
size to use sizeof, and limit the amount of data copied in another
memcpy call as well.

Signed-off-by: Xi Wang <xi.wang@gmail.com>
Signed-off-by: Martin Storsjö <martin@martin.st>
This commit is contained in:
Xi Wang 2013-01-22 21:40:05 -05:00 committed by Martin Storsjö
parent 3cff53369a
commit ecb918e5f0
1 changed files with 5 additions and 6 deletions
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11
libavformat/rtmppkt.c
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@ -440,7 +440,7 @@ static const char* rtmp_packet_type(int type)
static void ff_amf_tag_contents(void *ctx, const uint8_t *data, const uint8_t *data_end)
{
int size;
unsigned int size;
char buf[1024];
if (data >= data_end)
@ -459,7 +459,7 @@ static void ff_amf_tag_contents(void *ctx, const uint8_t *data, const uint8_t *d
} else {
size = bytestream_get_be32(&data);
}
size = FFMIN(size, 1023);
size = FFMIN(size, sizeof(buf) - 1);
memcpy(buf, data, size);
buf[size] = 0;
av_log(ctx, AV_LOG_DEBUG, " string '%s'\n", buf);
@ -472,16 +472,15 @@ static void ff_amf_tag_contents(void *ctx, const uint8_t *data, const uint8_t *d
case AMF_DATA_TYPE_OBJECT:
av_log(ctx, AV_LOG_DEBUG, " {\n");
for (;;) {
int size = bytestream_get_be16(&data);
int t;
memcpy(buf, data, size);
buf[size] = 0;
size = bytestream_get_be16(&data);
av_strlcpy(buf, data, FFMIN(sizeof(buf), size + 1));
if (!size) {
av_log(ctx, AV_LOG_DEBUG, " }\n");
data++;
break;
}
if (size < 0 || size >= data_end - data)
if (size >= data_end - data)
return;
data += size;
av_log(ctx, AV_LOG_DEBUG, " %s: ", buf);