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 <92siuy...@gmail.com>
---
net/ipv4/tcp_input.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 20f6fac..9775825 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;
--
2.7.4
