From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:33092) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aYFW6-00016I-M5 for qemu-devel@nongnu.org; Tue, 23 Feb 2016 11:08:51 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aYFW5-0003nT-7y for qemu-devel@nongnu.org; Tue, 23 Feb 2016 11:08:50 -0500 Received: from mx1.redhat.com ([209.132.183.28]:49240) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aYFW5-0003nO-2E for qemu-devel@nongnu.org; Tue, 23 Feb 2016 11:08:49 -0500 From: P J P Date: Tue, 23 Feb 2016 21:38:26 +0530 Message-Id: <1456243707-29345-2-git-send-email-ppandit@redhat.com> In-Reply-To: <1456243707-29345-1-git-send-email-ppandit@redhat.com> References: <1456243707-29345-1-git-send-email-ppandit@redhat.com> Subject: [Qemu-devel] [PATCH v2 1/2] net: check packet payload length List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Qemu Developers Cc: Jason Wang , Prasad J Pandit , Markus Armbruster , Liu Ling From: Prasad J Pandit 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 --- net/checksum.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) Update as per review: -> https://lists.gnu.org/archive/html/qemu-devel/2016-02/msg04062.html diff --git a/net/checksum.c b/net/checksum.c index 14c0855..bd89083 100644 --- a/net/checksum.c +++ b/net/checksum.c @@ -59,6 +59,11 @@ void net_checksum_calculate(uint8_t *data, int length) 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 *data, int length) return; } - if (plen < csum_offset+2) - return; + if (plen < csum_offset + 2 || plen + hlen >= length) { + return; + } data[14+hlen+csum_offset] = 0; data[14+hlen+csum_offset+1] = 0; -- 2.5.0