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")
Reported-by: Lucas Leong <wmliang@infosec.exchange>
Cc: stable@xxxxxxxxxx
Signed-off-by: Wander Lairson Costa <wander@xxxxxxxxxx>
---
net/netfilter/xt_sctp.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/net/netfilter/xt_sctp.c b/net/netfilter/xt_sctp.c
index e8961094a282..b46a6a512058 100644
--- a/net/netfilter/xt_sctp.c
+++ b/net/netfilter/xt_sctp.c
@@ -149,6 +149,8 @@ static int sctp_mt_check(const struct xt_mtchk_param *par)
{
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)
--
2.41.0
