From 362786f14a753d8a5256ef97d7c10ed576d6572b Mon Sep 17 00:00:00 2001 From: Prasad J Pandit Date: Wed, 2 Mar 2016 17:29:58 +0530 Subject: [PATCH] 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 Signed-off-by: Prasad J Pandit Signed-off-by: Jason Wang Upstream-Status: Backport CVE: CVE-2016-2857 http://git.qemu.org/?p=qemu.git;a=commit;h=362786f14a753d8a5256ef97d7c10ed576d6572b Signed-off-by: Armin Kuster --- net/checksum.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) Index: qemu-2.5.0/net/checksum.c =================================================================== --- qemu-2.5.0.orig/net/checksum.c +++ qemu-2.5.0/net/checksum.c @@ -59,6 +59,11 @@ void net_checksum_calculate(uint8_t *dat int hlen, plen, proto, csum_offset; uint16_t csum; + /* Ensure data has complete L2 & L3 headers. */ + if (length < 14 + 20) { + return; + } + if ((data[14] & 0xf0) != 0x40) return; /* not IPv4 */ hlen = (data[14] & 0x0f) * 4; @@ -76,8 +81,9 @@ void net_checksum_calculate(uint8_t *dat return; } - if (plen < csum_offset+2) - return; + if (plen < csum_offset + 2 || 14 + hlen + plen > length) { + return; + } data[14+hlen+csum_offset] = 0; data[14+hlen+csum_offset+1] = 0;