Message ID | 20220517205036.25883-1-fw@strlen.de |
---|---|
State | Accepted |
Delegated to: | Pablo Neira |
Headers | show |
Series | [nf-next] netfilter: cttimeout: fix slab-out-of-bounds read in cttimeout_net_exit | expand |
On Tue, May 17, 2022 at 10:50:36PM +0200, Florian Westphal wrote: > 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. Applied, thanks
diff --git a/net/netfilter/nfnetlink_cttimeout.c b/net/netfilter/nfnetlink_cttimeout.c index f069c24c6146..af15102bc696 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 {
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: <syzbot+92968395eedbdbd3617d@syzkaller.appspotmail.com> Fixes: 78222bacfca9 ("netfilter: cttimeout: decouple unlink and free on netns destruction") Signed-off-by: Florian Westphal <fw@strlen.de> --- net/netfilter/nfnetlink_cttimeout.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)