net: ipv6: fib: don't sleep inside atomic lock
The function fib6_commit_metrics() allocates a piece of memory in mode
GFP_KERNEL while holding an atomic lock from higher up in the stack, in
the function __ip6_ins_rt(). This produces the following BUG:
> BUG: sleeping function called from invalid context at mm/slub.c:1250
> in_atomic(): 1, irqs_disabled(): 0, pid: 2909, name: dhcpcd
> 2 locks held by dhcpcd/2909:
> #0: (rtnl_mutex){+.+.+.}, at: [<ffffffff81978e67>] rtnl_lock+0x17/0x20
> #1: (&tb->tb6_lock){++--+.}, at: [<ffffffff81a6951a>] ip6_route_add+0x65a/0x800
> CPU: 1 PID: 2909 Comm: dhcpcd Not tainted 3.17.0-rc1 #1
> Hardware name: ASUS All Series/Q87T, BIOS 0216 10/16/2013
> 0000000000000008 ffff8800c8f13858 ffffffff81af135a 0000000000000000
> ffff880212202430 ffff8800c8f13878 ffffffff810f8d3a ffff880212202c98
> 0000000000000010 ffff8800c8f138c8 ffffffff8121ad0e 0000000000000001
> Call Trace:
> [<ffffffff81af135a>] dump_stack+0x4e/0x68
> [<ffffffff810f8d3a>] __might_sleep+0x10a/0x120
> [<ffffffff8121ad0e>] kmem_cache_alloc_trace+0x4e/0x190
> [<ffffffff81a6bcd6>] ? fib6_commit_metrics+0x66/0x110
> [<ffffffff81a6bcd6>] fib6_commit_metrics+0x66/0x110
> [<ffffffff81a6cbf3>] fib6_add+0x883/0xa80
> [<ffffffff81a6951a>] ? ip6_route_add+0x65a/0x800
> [<ffffffff81a69535>] ip6_route_add+0x675/0x800
> [<ffffffff81a68f2a>] ? ip6_route_add+0x6a/0x800
> [<ffffffff81a6990c>] inet6_rtm_newroute+0x5c/0x80
> [<ffffffff8197cf01>] rtnetlink_rcv_msg+0x211/0x260
> [<ffffffff81978e67>] ? rtnl_lock+0x17/0x20
> [<ffffffff81119708>] ? lock_release_holdtime+0x28/0x180
> [<ffffffff81978e67>] ? rtnl_lock+0x17/0x20
> [<ffffffff8197ccf0>] ? __rtnl_unlock+0x20/0x20
> [<ffffffff819a989e>] netlink_rcv_skb+0x6e/0xd0
> [<ffffffff81978ee5>] rtnetlink_rcv+0x25/0x40
> [<ffffffff819a8e59>] netlink_unicast+0xd9/0x180
> [<ffffffff819a9600>] netlink_sendmsg+0x700/0x770
> [<ffffffff81103735>] ? local_clock+0x25/0x30
> [<ffffffff8194e83c>] sock_sendmsg+0x6c/0x90
> [<ffffffff811f98e3>] ? might_fault+0xa3/0xb0
> [<ffffffff8195ca6d>] ? verify_iovec+0x7d/0xf0
> [<ffffffff8194ec3e>] ___sys_sendmsg+0x37e/0x3b0
> [<ffffffff8111ef15>] ? trace_hardirqs_on_caller+0x185/0x220
> [<ffffffff81af979e>] ? mutex_unlock+0xe/0x10
> [<ffffffff819a55ec>] ? netlink_insert+0xbc/0xe0
> [<ffffffff819a65e5>] ? netlink_autobind.isra.30+0x125/0x150
> [<ffffffff819a6520>] ? netlink_autobind.isra.30+0x60/0x150
> [<ffffffff819a84f9>] ? netlink_bind+0x159/0x230
> [<ffffffff811f989a>] ? might_fault+0x5a/0xb0
> [<ffffffff8194f25e>] ? SYSC_bind+0x7e/0xd0
> [<ffffffff8194f8cd>] __sys_sendmsg+0x4d/0x80
> [<ffffffff8194f912>] SyS_sendmsg+0x12/0x20
> [<ffffffff81afc692>] system_call_fastpath+0x16/0x1b
Fixing this by replacing the mode GFP_KERNEL with GFP_ATOMIC.
Signed-off-by: Benjamin Block <bebl@mageta.org>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index cb4459b..76b7f5e 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -643,7 +643,7 @@
if (dst->flags & DST_HOST) {
mp = dst_metrics_write_ptr(dst);
} else {
- mp = kzalloc(sizeof(u32) * RTAX_MAX, GFP_KERNEL);
+ mp = kzalloc(sizeof(u32) * RTAX_MAX, GFP_ATOMIC);
if (!mp)
return -ENOMEM;
dst_init_metrics(dst, mp, 0);