When the last byte of options is a non-single-byte option kind, walkers that advance with i += op[i + 1] ? : 1 can read op[i + 1] past the end of the option area. Add an explicit i == optlen - 1 check before dereferencing op[i + 1] in xt_tcpudp and xt_dccp option walkers. Fixes: 2e4e6a17af35 ("[NETFILTER] x_tables: Abstraction layer for {ip,ip6,arp}_tables") Cc: fw@strlen.de Cc: stable@vger.kernel.org Signed-off-by: David Dull --- net/netfilter/xt_dccp.c | 4 ++-- net/netfilter/xt_tcpudp.c | 6 ++++-- 2 files changed, 5 insertions(+), 4 deletions(-) diff --git a/net/netfilter/xt_dccp.c b/net/netfilter/xt_dccp.c index e5a13ecbe6..037ab93e25 100644 --- a/net/netfilter/xt_dccp.c +++ b/net/netfilter/xt_dccp.c @@ -62,10 +62,10 @@ dccp_find_option(u_int8_t option, return true; } - if (op[i] < 2) + if (op[i] < 2 || i == optlen - 1) i++; else - i += op[i+1]?:1; + i += op[i + 1] ? : 1; } spin_unlock_bh(&dccp_buflock); diff --git a/net/netfilter/xt_tcpudp.c b/net/netfilter/xt_tcpudp.c index e8991130a3..f76cf18f1a 100644 --- a/net/netfilter/xt_tcpudp.c +++ b/net/netfilter/xt_tcpudp.c @@ -59,8 +59,10 @@ tcp_find_option(u_int8_t option, for (i = 0; i < optlen; ) { if (op[i] == option) return !invert; - if (op[i] < 2) i++; - else i += op[i+1]?:1; + if (op[i] < 2 || i == optlen - 1) + i++; + else + i += op[i + 1] ? : 1; } return invert; -- 2.43.0