[PATCH 5.10 271/406] netfilter: xt_sctp: validate the flag_info count

Greg Kroah-Hartman
2023-09-17T19:35:57Z

From: Wander Lairson Costa <wander@redhat.com>

commit e99476497687ef9e850748fe6d232264f30bc8f9 upstream.

sctp_mt_check doesn't validate the flag_count field. An attacker can
take advantage of that to trigger a OOB read and leak memory
information.

Add the field validation in the checkentry function.

Fixes: 2e4e6a17af35 ("[NETFILTER] x_tables: Abstraction layer for {ip,ip6,arp}_tables")
Cc: stable@vger.kernel.org
Reported-by: Lucas Leong <wmliang@infosec.exchange>
Signed-off-by: Wander Lairson Costa <wander@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/netfilter/xt_sctp.c | 2 ++
1 file changed, 2 insertions(+)

--- a/net/netfilter/xt_sctp.c
+++ b/net/netfilter/xt_sctp.c
@@ -150,6 +150,8 @@ static int sctp_mt_check(const struct xt
{
const struct xt_sctp_info *info = par->matchinfo;

+ if (info->flag_count > ARRAY_SIZE(info->flag_info))
+ return -EINVAL;
if (info->flags & ~XT_SCTP_VALID_FLAGS)
return -EINVAL;
if (info->invflags & ~XT_SCTP_VALID_FLAGS)