From d2493f291d06e50a2a9d9d70634a3e1784045473 Mon Sep 17 00:00:00 2001 From: Jia-Ju Bai Date: Tue, 23 Jul 2019 18:00:15 +0800 Subject: [PATCH] security: smack: Fix possible null-pointer dereferences in smack_socket_sock_rcv_skb() BugLink: https://bugs.launchpad.net/bugs/1848274 [ Upstream commit 3f4287e7d98a2954f20bf96c567fdffcd2b63eb9 ] In smack_socket_sock_rcv_skb(), there is an if statement on line 3920 to check whether skb is NULL: if (skb && skb->secmark != 0) This check indicates skb can be NULL in some cases. But on lines 3931 and 3932, skb is used: ad.a.u.net->netif = skb->skb_iif; ipv6_skb_to_auditdata(skb, &ad.a, NULL); Thus, possible null-pointer dereferences may occur when skb is NULL. To fix these possible bugs, an if statement is added to check skb. These bugs are found by a static analysis tool STCheck written by us. Signed-off-by: Jia-Ju Bai Signed-off-by: Casey Schaufler Signed-off-by: Sasha Levin Signed-off-by: Kamal Mostafa Signed-off-by: Kleber Sacilotto de Souza --- security/smack/smack_lsm.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c index 0d45c7884f50..e593d449672b 100644 --- a/security/smack/smack_lsm.c +++ b/security/smack/smack_lsm.c @@ -3839,6 +3839,8 @@ access_check: skp = smack_ipv6host_label(&sadd); if (skp == NULL) skp = smack_net_ambient; + if (skb == NULL) + break; #ifdef CONFIG_AUDIT smk_ad_init_net(&ad, __func__, LSM_AUDIT_DATA_NET, &net); ad.a.u.net->family = family; -- 2.39.2