From: Pablo Neira Ayuso Date: Wed, 9 Dec 2015 11:09:56 +0000 (+0100) Subject: netfilter: nfnetlink: fix splat due to incorrect socket memory accounting in skbuff... X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=bd678e09dc1797bc0e2e536b6b268e7cf46e0184;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git netfilter: nfnetlink: fix splat due to incorrect socket memory accounting in skbuff clones If we attach the sk to the skb from nfnetlink_rcv_batch(), then netlink_skb_destructor() will underflow the socket receive memory counter and we get warning splat when releasing the socket. $ cat /proc/net/netlink sk Eth Pid Groups Rmem Wmem Dump Locks Drops Inode ffff8800ca903000 12 0 00000000 -54144 0 0 2 0 17942 ^^^^^^ Rmem above shows an underflow. And here below the warning splat: [ 1363.815976] WARNING: CPU: 2 PID: 1356 at net/netlink/af_netlink.c:958 netlink_sock_destruct+0x80/0xb9() [...] [ 1363.816152] CPU: 2 PID: 1356 Comm: kworker/u16:1 Tainted: G W 4.4.0-rc1+ #153 [ 1363.816155] Hardware name: LENOVO 23259H1/23259H1, BIOS G2ET32WW (1.12 ) 05/30/2012 [ 1363.816160] Workqueue: netns cleanup_net [ 1363.816163] 0000000000000000 ffff880119203dd0 ffffffff81240204 0000000000000000 [ 1363.816169] ffff880119203e08 ffffffff8104db4b ffffffff813d49a1 ffff8800ca771000 [ 1363.816174] ffffffff81a42b00 0000000000000000 ffff8800c0afe1e0 ffff880119203e18 [ 1363.816179] Call Trace: [ 1363.816181] [] dump_stack+0x4e/0x79 [ 1363.816193] [] warn_slowpath_common+0x9a/0xb3 [ 1363.816197] [] ? netlink_sock_destruct+0x80/0xb9 skb->sk was only needed to lookup for the netns, however we don't need this anymore since 633c9a840d0b ("netfilter: nfnetlink: avoid recurrent netns lookups in call_batch") so this patch removes this manual socket assignment to resolve this problem. Reported-by: Arturo Borrero Gonzalez Reported-by: Ben Hutchings Signed-off-by: Pablo Neira Ayuso Tested-by: Arturo Borrero Gonzalez --- diff --git a/net/netfilter/nfnetlink.c b/net/netfilter/nfnetlink.c index 445590f2c673..77afe913d03d 100644 --- a/net/netfilter/nfnetlink.c +++ b/net/netfilter/nfnetlink.c @@ -295,8 +295,6 @@ replay: if (!skb) return netlink_ack(oskb, nlh, -ENOMEM); - skb->sk = oskb->sk; - nfnl_lock(subsys_id); ss = rcu_dereference_protected(table[subsys_id].subsys, lockdep_is_held(&table[subsys_id].mutex));