From 107987e8f8c8ec66d0cc110b90e47b08d4a6f764 Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Fri, 20 May 2022 00:02:05 +0200 Subject: [PATCH] netfilter: cttimeout: fix slab-out-of-bounds read in cttimeout_net_exit syzbot reports: BUG: KASAN: slab-out-of-bounds in __list_del_entry_valid+0xcc/0xf0 lib/list_debug.c:42 [..] list_del include/linux/list.h:148 [inline] cttimeout_net_exit+0x211/0x540 net/netfilter/nfnetlink_cttimeout.c:617 No reproducer so far. Looking at recent changes in this area its clear that the free_head must not be at the end of the structure because nf_ct_timeout structure has variable size. Reported-by: Fixes: 7336c1976b8c ("netfilter: cttimeout: decouple unlink and free on netns destruction") Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nfnetlink_cttimeout.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/net/netfilter/nfnetlink_cttimeout.c b/net/netfilter/nfnetlink_cttimeout.c index f069c24c61461..af15102bc696f 100644 --- a/net/netfilter/nfnetlink_cttimeout.c +++ b/net/netfilter/nfnetlink_cttimeout.c @@ -35,12 +35,13 @@ static unsigned int nfct_timeout_id __read_mostly; struct ctnl_timeout { struct list_head head; + struct list_head free_head; struct rcu_head rcu_head; refcount_t refcnt; char name[CTNL_TIMEOUT_NAME_MAX]; - struct nf_ct_timeout timeout; - struct list_head free_head; + /* must be at the end */ + struct nf_ct_timeout timeout; }; struct nfct_timeout_pernet { -- 2.39.5