From 9609dad263f8bea347f41fddca29353dbf8a7d37 Mon Sep 17 00:00:00 2001 From: Young Xiao <92siuyang@gmail.com> Date: Wed, 29 May 2019 16:10:59 +0800 Subject: ipv4: tcp_input: fix stack out of bounds when parsing TCP options. The TCP option parsing routines in tcp_parse_options function could read one byte out of the buffer of the TCP options. 1 while (length > 0) { 2 int opcode = *ptr++; 3 int opsize; 4 5 switch (opcode) { 6 case TCPOPT_EOL: 7 return; 8 case TCPOPT_NOP: /* Ref: RFC 793 section 3.1 */ 9 length--; 10 continue; 11 default: 12 opsize = *ptr++; //out of bound access If length = 1, then there is an access in line2. And another access is occurred in line 12. This would lead to out-of-bound access. Therefore, in the patch we check that the available data length is larger enough to pase both TCP option code and size. Signed-off-by: Young Xiao <92siuyang@gmail.com> Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv4/tcp_input.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'net/ipv4/tcp_input.c') diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index c61edd023b35..08a477e74cf3 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -3791,6 +3791,8 @@ void tcp_parse_options(const struct net *net, length--; continue; default: + if (length < 2) + return; opsize = *ptr++; if (opsize < 2) /* "silly options" */ return; -- cgit v1.2.3-59-g8ed1b