From e8d411d2980723b8f8ba8e4dd78b694c5fd9ea3e Mon Sep 17 00:00:00 2001 From: Xin Long Date: Mon, 28 Aug 2017 10:45:01 +0800 Subject: [PATCH] ipv6: do not set sk_destruct in IPV6_ADDRFORM sockopt ChunYu found a kernel warn_on during syzkaller fuzzing: [40226.038539] WARNING: CPU: 5 PID: 23720 at net/ipv4/af_inet.c:152 inet_sock_destruct+0x78d/0x9a0 [40226.144849] Call Trace: [40226.147590] [40226.149859] dump_stack+0xe2/0x186 [40226.176546] __warn+0x1a4/0x1e0 [40226.180066] warn_slowpath_null+0x31/0x40 [40226.184555] inet_sock_destruct+0x78d/0x9a0 [40226.246355] __sk_destruct+0xfa/0x8c0 [40226.290612] rcu_process_callbacks+0xaa0/0x18a0 [40226.336816] __do_softirq+0x241/0x75e [40226.367758] irq_exit+0x1f6/0x220 [40226.371458] smp_apic_timer_interrupt+0x7b/0xa0 [40226.376507] apic_timer_interrupt+0x93/0xa0 The warn_on happned when sk->sk_rmem_alloc wasn't 0 in inet_sock_destruct. As after commit f970bd9e3a06 ("udp: implement memory accounting helpers"), udp has changed to use udp_destruct_sock as sk_destruct where it would udp_rmem_release all rmem. But IPV6_ADDRFORM sockopt sets sk_destruct with inet_sock_destruct after changing family to PF_INET. If rmem is not 0 at that time, and there is no place to release rmem before calling inet_sock_destruct, the warn_on will be triggered. This patch is to fix it by not setting sk_destruct in IPV6_ADDRFORM sockopt any more. As IPV6_ADDRFORM sockopt only works for tcp and udp. TCP sock has already set it's sk_destruct with inet_sock_destruct and UDP has set with udp_destruct_sock since they're created. Fixes: f970bd9e3a06 ("udp: implement memory accounting helpers") Reported-by: ChunYu Wang Signed-off-by: Xin Long Acked-by: Paolo Abeni Signed-off-by: David S. Miller --- net/ipv6/ipv6_sockglue.c | 1 - 1 file changed, 1 deletion(-) diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c index 02d795fe3d7f..a5e466d4e093 100644 --- a/net/ipv6/ipv6_sockglue.c +++ b/net/ipv6/ipv6_sockglue.c @@ -242,7 +242,6 @@ static int do_ipv6_setsockopt(struct sock *sk, int level, int optname, pktopt = xchg(&np->pktoptions, NULL); kfree_skb(pktopt); - sk->sk_destruct = inet_sock_destruct; /* * ... and add it to the refcnt debug socks count * in the new family. -acme -- 2.20.1