From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:33552) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1adCSx-0006Vm-JY for qemu-devel@nongnu.org; Tue, 08 Mar 2016 02:54:04 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1adCSu-0000Ha-Ai for qemu-devel@nongnu.org; Tue, 08 Mar 2016 02:54:03 -0500 Received: from mx1.redhat.com ([209.132.183.28]:36659) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1adCSu-0000HU-5R for qemu-devel@nongnu.org; Tue, 08 Mar 2016 02:54:00 -0500 From: Jason Wang Date: Tue, 8 Mar 2016 15:52:44 +0800 Message-Id: <1457423564-9724-13-git-send-email-jasowang@redhat.com> In-Reply-To: <1457423564-9724-1-git-send-email-jasowang@redhat.com> References: <1457423564-9724-1-git-send-email-jasowang@redhat.com> Subject: [Qemu-devel] [PULL V2 12/12] net: check packet payload length List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: peter.maydell@linaro.org, qemu-devel@nongnu.org Cc: Jason Wang , Prasad J Pandit 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 Signed-off-by: Jason Wang --- net/checksum.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/net/checksum.c b/net/checksum.c index b5016ab..d0fa424 100644 --- a/net/checksum.c +++ b/net/checksum.c @@ -60,6 +60,11 @@ 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; @@ -77,8 +82,9 @@ void net_checksum_calculate(uint8_t *data, int length) 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; -- 2.5.0