From: Eric Dumazet edumazet@google.com
[ Upstream commit c543cb4a5f07e09237ec0fc2c60c9f131b2c79ad ]
fib_compute_spec_dst() needs to be called under rcu protection.
syzbot reported :
WARNING: suspicious RCU usage 5.1.0-rc4+ #165 Not tainted include/linux/inetdevice.h:220 suspicious rcu_dereference_check() usage!
other info that might help us debug this:
rcu_scheduler_active = 2, debug_locks = 1 1 lock held by swapper/0/0: #0: 0000000051b67925 ((&n->timer)){+.-.}, at: lockdep_copy_map include/linux/lockdep.h:170 [inline] #0: 0000000051b67925 ((&n->timer)){+.-.}, at: call_timer_fn+0xda/0x720 kernel/time/timer.c:1315
stack backtrace: CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.1.0-rc4+ #165 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: <IRQ> __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x172/0x1f0 lib/dump_stack.c:113 lockdep_rcu_suspicious+0x153/0x15d kernel/locking/lockdep.c:5162 __in_dev_get_rcu include/linux/inetdevice.h:220 [inline] fib_compute_spec_dst+0xbbd/0x1030 net/ipv4/fib_frontend.c:294 spec_dst_fill net/ipv4/ip_options.c:245 [inline] __ip_options_compile+0x15a7/0x1a10 net/ipv4/ip_options.c:343 ipv4_link_failure+0x172/0x400 net/ipv4/route.c:1195 dst_link_failure include/net/dst.h:427 [inline] arp_error_report+0xd1/0x1c0 net/ipv4/arp.c:297 neigh_invalidate+0x24b/0x570 net/core/neighbour.c:995 neigh_timer_handler+0xc35/0xf30 net/core/neighbour.c:1081 call_timer_fn+0x190/0x720 kernel/time/timer.c:1325 expire_timers kernel/time/timer.c:1362 [inline] __run_timers kernel/time/timer.c:1681 [inline] __run_timers kernel/time/timer.c:1649 [inline] run_timer_softirq+0x652/0x1700 kernel/time/timer.c:1694 __do_softirq+0x266/0x95a kernel/softirq.c:293 invoke_softirq kernel/softirq.c:374 [inline] irq_exit+0x180/0x1d0 kernel/softirq.c:414 exiting_irq arch/x86/include/asm/apic.h:536 [inline] smp_apic_timer_interrupt+0x14a/0x570 arch/x86/kernel/apic/apic.c:1062 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:807
Fixes: ed0de45a1008 ("ipv4: recompile ip options in ipv4_link_failure") Signed-off-by: Eric Dumazet edumazet@google.com Reported-by: syzbot syzkaller@googlegroups.com Cc: Stephen Suryaputra ssuryaextr@gmail.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/ipv4/route.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)
--- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -1194,14 +1194,20 @@ static struct dst_entry *ipv4_dst_check(
static void ipv4_link_failure(struct sk_buff *skb) { - struct rtable *rt; struct ip_options opt; + struct rtable *rt; + int res;
/* Recompile ip options since IPCB may not be valid anymore. */ memset(&opt, 0, sizeof(opt)); opt.optlen = ip_hdr(skb)->ihl*4 - sizeof(struct iphdr); - if (__ip_options_compile(dev_net(skb->dev), &opt, skb, NULL)) + + rcu_read_lock(); + res = __ip_options_compile(dev_net(skb->dev), &opt, skb, NULL); + rcu_read_unlock(); + + if (res) return;
__icmp_send(skb, ICMP_DEST_UNREACH, ICMP_HOST_UNREACH, 0, &opt);