From: Florian Westphal Date: Thu, 19 May 2022 22:02:05 +0000 (+0200) Subject: netfilter: cttimeout: fix slab-out-of-bounds read in cttimeout_net_exit X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=aeed55a08d0b2bf2e3986b110b04d2a5aca192a6;p=linux.git 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: 78222bacfca9 ("netfilter: cttimeout: decouple unlink and free on netns destruction") Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- 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 {