net: check packet payload length
While computing IP checksum, 'net_checksum_calculate' reads
payload length from the packet. It could exceed the given 'data'
buffer size. Add a check to avoid it.
Reported-by: Liu Ling <liuling-it@360.cn>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Signed-off-by: Jason Wang <jasowang@redhat.com>
(cherry picked from commit 362786f14a)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
			
			
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					@ -59,6 +59,11 @@ void net_checksum_calculate(uint8_t *data, int length)
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    int hlen, plen, proto, csum_offset;
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					    int hlen, plen, proto, csum_offset;
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    uint16_t csum;
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					    uint16_t csum;
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					    /* Ensure data has complete L2 & L3 headers. */
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					    if (length < 14 + 20) {
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					        return;
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					    }
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    if ((data[14] & 0xf0) != 0x40)
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					    if ((data[14] & 0xf0) != 0x40)
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	return; /* not IPv4 */
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						return; /* not IPv4 */
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    hlen  = (data[14] & 0x0f) * 4;
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					    hlen  = (data[14] & 0x0f) * 4;
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					@ -76,8 +81,9 @@ void net_checksum_calculate(uint8_t *data, int length)
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	return;
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						return;
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    }
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					    }
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    if (plen < csum_offset+2)
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					    if (plen < csum_offset + 2 || 14 + hlen + plen > length) {
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	return;
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					        return;
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					    }
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    data[14+hlen+csum_offset]   = 0;
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					    data[14+hlen+csum_offset]   = 0;
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    data[14+hlen+csum_offset+1] = 0;
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					    data[14+hlen+csum_offset+1] = 0;
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