From 412096b75ab81224fa896e74179dc74b2cba6e28 Mon Sep 17 00:00:00 2001 From: Maxim Mikityanskiy Date: Thu, 10 Jun 2021 19:40:30 +0300 Subject: [PATCH] mptcp: Fix out of bounds when parsing TCP options The TCP option parser in mptcp (mptcp_get_options) could read one byte out of bounds. When the length is 1, the execution flow gets into the loop, reads one byte of the opcode, and if the opcode is neither TCPOPT_EOL nor TCPOPT_NOP, it reads one more byte, which exceeds the length of 1. This fix is inspired by commit fae93b8ae922 ("ipv4: tcp_input: fix stack out of bounds when parsing TCP options."). Cc: Young Xiao <92siuyang@gmail.com> Fixes: 67d38781cb8e ("mptcp: Handle MP_CAPABLE options for outgoing connections") Signed-off-by: Maxim Mikityanskiy Reviewed-by: Mat Martineau Signed-off-by: David S. Miller --- net/mptcp/options.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/mptcp/options.c b/net/mptcp/options.c index 6b825fb3fa832..9b263f27ce9bd 100644 --- a/net/mptcp/options.c +++ b/net/mptcp/options.c @@ -356,6 +356,8 @@ void mptcp_get_options(const struct sk_buff *skb, length--; continue; default: + if (length < 2) + return; opsize = *ptr++; if (opsize < 2) /* "silly options" */ return; -- 2.39.5