3.2.102-rc1 review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet edumazet@google.com
commit e7aadb27a5415e8125834b84a74477bfbee4eff5 upstream.
Newly added igmpv3_get_srcaddr() needs to be called under rcu lock.
Timer callbacks do not ensure this locking.
============================= WARNING: suspicious RCU usage 4.15.0+ #200 Not tainted ----------------------------- ./include/linux/inetdevice.h:216 suspicious rcu_dereference_check() usage!
other info that might help us debug this:
rcu_scheduler_active = 2, debug_locks = 1 3 locks held by syzkaller616973/4074: #0: (&mm->mmap_sem){++++}, at: [<00000000bfce669e>] __do_page_fault+0x32d/0xc90 arch/x86/mm/fault.c:1355 #1: ((&im->timer)){+.-.}, at: [<00000000619d2f71>] lockdep_copy_map include/linux/lockdep.h:178 [inline] #1: ((&im->timer)){+.-.}, at: [<00000000619d2f71>] call_timer_fn+0x1c6/0x820 kernel/time/timer.c:1316 #2: (&(&im->lock)->rlock){+.-.}, at: [<000000005f833c5c>] spin_lock_bh include/linux/spinlock.h:315 [inline] #2: (&(&im->lock)->rlock){+.-.}, at: [<000000005f833c5c>] igmpv3_send_report+0x98/0x5b0 net/ipv4/igmp.c:600
stack backtrace: CPU: 0 PID: 4074 Comm: syzkaller616973 Not tainted 4.15.0+ #200 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: <IRQ> __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x194/0x257 lib/dump_stack.c:53 lockdep_rcu_suspicious+0x123/0x170 kernel/locking/lockdep.c:4592 __in_dev_get_rcu include/linux/inetdevice.h:216 [inline] igmpv3_get_srcaddr net/ipv4/igmp.c:329 [inline] igmpv3_newpack+0xeef/0x12e0 net/ipv4/igmp.c:389 add_grhead.isra.27+0x235/0x300 net/ipv4/igmp.c:432 add_grec+0xbd3/0x1170 net/ipv4/igmp.c:565 igmpv3_send_report+0xd5/0x5b0 net/ipv4/igmp.c:605 igmp_send_report+0xc43/0x1050 net/ipv4/igmp.c:722 igmp_timer_expire+0x322/0x5c0 net/ipv4/igmp.c:831 call_timer_fn+0x228/0x820 kernel/time/timer.c:1326 expire_timers kernel/time/timer.c:1363 [inline] __run_timers+0x7ee/0xb70 kernel/time/timer.c:1666 run_timer_softirq+0x4c/0x70 kernel/time/timer.c:1692 __do_softirq+0x2d7/0xb85 kernel/softirq.c:285 invoke_softirq kernel/softirq.c:365 [inline] irq_exit+0x1cc/0x200 kernel/softirq.c:405 exiting_irq arch/x86/include/asm/apic.h:541 [inline] smp_apic_timer_interrupt+0x16b/0x700 arch/x86/kernel/apic/apic.c:1052 apic_timer_interrupt+0xa9/0xb0 arch/x86/entry/entry_64.S:938
Fixes: a46182b00290 ("net: igmp: Use correct source address on IGMPv3 reports") Signed-off-by: Eric Dumazet edumazet@google.com Reported-by: syzbot syzkaller@googlegroups.com
Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Ben Hutchings ben@decadent.org.uk --- net/ipv4/igmp.c | 4 ++++ 1 file changed, 4 insertions(+)
--- a/net/ipv4/igmp.c +++ b/net/ipv4/igmp.c @@ -363,7 +363,11 @@ static struct sk_buff *igmpv3_newpack(st pip->frag_off = htons(IP_DF); pip->ttl = 1; pip->daddr = fl4.daddr; + + rcu_read_lock(); pip->saddr = igmpv3_get_srcaddr(dev, &fl4); + rcu_read_unlock(); + pip->protocol = IPPROTO_IGMP; pip->tot_len = 0; /* filled in later */ ip_select_ident(skb, NULL);