diff options
| author | Eric Dumazet <edumazet@google.com> | 2025-06-27 11:46:41 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2025-06-28 10:44:21 +0100 |
| commit | beead7eea896e5bc803027d1f3e0d0f9c3b9d196 (patch) | |
| tree | 5d457bb2612115b56a01b7db2276e7cd8fcda79f | |
| parent | f22e6fdf7b3395a627a1ad06ab70835015f7ff17 (diff) | |
net: ipv4: guard ip_mr_output() with rcu
syzbot found at least one path leads to an ip_mr_output()
without RCU being held.
Add guard(rcu)() to fix this in a concise way.
WARNING: CPU: 0 PID: 0 at net/ipv4/ipmr.c:2302 ip_mr_output+0xbb1/0xe70 net/ipv4/ipmr.c:2302
Call Trace:
<IRQ>
igmp_send_report+0x89e/0xdb0 net/ipv4/igmp.c:799
igmp_timer_expire+0x204/0x510 net/ipv4/igmp.c:-1
call_timer_fn+0x17e/0x5f0 kernel/time/timer.c:1747
expire_timers kernel/time/timer.c:1798 [inline]
__run_timers kernel/time/timer.c:2372 [inline]
__run_timer_base+0x61a/0x860 kernel/time/timer.c:2384
run_timer_base kernel/time/timer.c:2393 [inline]
run_timer_softirq+0xb7/0x180 kernel/time/timer.c:2403
handle_softirqs+0x286/0x870 kernel/softirq.c:579
__do_softirq kernel/softirq.c:613 [inline]
invoke_softirq kernel/softirq.c:453 [inline]
__irq_exit_rcu+0xca/0x1f0 kernel/softirq.c:680
irq_exit_rcu+0x9/0x30 kernel/softirq.c:696
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline]
sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1050
Fixes: 35bec72a24ac ("net: ipv4: Add ip_mr_output()")
Reported-by: syzbot+f02fb9e43bd85c6c66ae@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/685e841a.a00a0220.129264.0002.GAE@google.com/T/#u
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Petr Machata <petrm@nvidia.com>
Cc: Roopa Prabhu <roopa@nvidia.com>
Cc: Nikolay Aleksandrov <razor@blackwall.org>
Cc: Benjamin Poirier <bpoirier@nvidia.com>
Cc: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Neal Cardwell <ncardwell@google.com>
Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org>
Reviewed-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | net/ipv4/ipmr.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c index f78c4e53dc8c..3a2044e6033d 100644 --- a/net/ipv4/ipmr.c +++ b/net/ipv4/ipmr.c @@ -2299,7 +2299,8 @@ int ip_mr_output(struct net *net, struct sock *sk, struct sk_buff *skb) struct mr_table *mrt; int vif; - WARN_ON_ONCE(!rcu_read_lock_held()); + guard(rcu)(); + dev = rt->dst.dev; if (IPCB(skb)->flags & IPSKB_FORWARDED) @@ -2313,7 +2314,6 @@ int ip_mr_output(struct net *net, struct sock *sk, struct sk_buff *skb) if (IS_ERR(mrt)) goto mc_output; - /* already under rcu_read_lock() */ cache = ipmr_cache_find(mrt, ip_hdr(skb)->saddr, ip_hdr(skb)->daddr); if (!cache) { vif = ipmr_find_vif(mrt, dev); |