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rtmp: fix multiple broken overflow checks 

Sanity checks like `data + size >= data_end || data + size < data' are
broken, because `data + size < data' assumes pointer overflow, which is
undefined behavior in C.  Many compilers such as gcc/clang optimize such
checks away.

Use `size < 0 || size >= data_end - data' instead.

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 17:49:29 -05:00 committed by Martin Storsjö
parent 2e4130037c
commit 3cff53369a
1 changed files with 6 additions and 6 deletions
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12
libavformat/rtmppkt.c
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@ -356,11 +356,11 @@ int ff_amf_tag_size(const uint8_t *data, const uint8_t *data_end)
data++;
break;
}
if (data + size >= data_end || data + size < data)
if (size < 0 || size >= data_end - data)
return -1;
data += size;
t = ff_amf_tag_size(data, data_end);
if (t < 0 || data + t >= data_end)
if (t < 0 || t >= data_end - data)
return -1;
data += t;
}
@ -389,7 +389,7 @@ int ff_amf_get_field_value(const uint8_t *data, const uint8_t *data_end,
int size = bytestream_get_be16(&data);
if (!size)
break;
if (data + size >= data_end || data + size < data)
if (size < 0 || size >= data_end - data)
return -1;
data += size;
if (size == namelen && !memcmp(data-size, name, namelen)) {
@ -410,7 +410,7 @@ int ff_amf_get_field_value(const uint8_t *data, const uint8_t *data_end,
return 0;
}
len = ff_amf_tag_size(data, data_end);
if (len < 0 || data + len >= data_end || data + len < data)
if (len < 0 || len >= data_end - data)
return -1;
data += len;
}
@ -481,13 +481,13 @@ static void ff_amf_tag_contents(void *ctx, const uint8_t *data, const uint8_t *d
data++;
break;
}
if (data + size >= data_end || data + size < data)
if (size < 0 || size >= data_end - data)
return;
data += size;
av_log(ctx, AV_LOG_DEBUG, " %s: ", buf);
ff_amf_tag_contents(ctx, data, data_end);
t = ff_amf_tag_size(data, data_end);
if (t < 0 || data + t >= data_end)
if (t < 0 || t >= data_end - data)
return;
data += t;
}