Message ID | 20200520114529.3433-1-penguin-kernel@I-love.SAKURA.ne.jp |
---|---|
State | Changes Requested |
Delegated to: | David Miller |
Headers | show |
Series | tipc: Disable preemption when calling send_msg method. | expand |
On 5/20/20 4:45 AM, Tetsuo Handa wrote: > syzbot is reporting that tipc_udp_send_msg() is calling dst_cache_get() > without preemption disabled [1]. Since b->media->send_msg() is called > with RCU lock already held, we can also disable preemption at that point. > > [1] https://syzkaller.appspot.com/bug?id=dc6352b92862eb79373fe03fdf9af5928753e057 > > Reported-by: syzbot+1a68504d96cd17b33a05@syzkaller.appspotmail.com > Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> > --- > net/tipc/bearer.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/net/tipc/bearer.c b/net/tipc/bearer.c > index 34ca7b789eba..e5cf91665881 100644 > --- a/net/tipc/bearer.c > +++ b/net/tipc/bearer.c > @@ -516,6 +516,7 @@ void tipc_bearer_xmit_skb(struct net *net, u32 bearer_id, > struct tipc_msg *hdr = buf_msg(skb); > struct tipc_bearer *b; > > + preempt_disable(); > rcu_read_lock(); > b = bearer_get(net, bearer_id); > if (likely(b && (test_bit(0, &b->up) || msg_is_reset(hdr)))) { > @@ -528,6 +529,7 @@ void tipc_bearer_xmit_skb(struct net *net, u32 bearer_id, > kfree_skb(skb); > } > rcu_read_unlock(); > + preempt_enable(); > } > > /* tipc_bearer_xmit() -send buffer to destination over bearer > @@ -543,6 +545,7 @@ void tipc_bearer_xmit(struct net *net, u32 bearer_id, > if (skb_queue_empty(xmitq)) > return; > > + preempt_disable(); > rcu_read_lock(); > b = bearer_get(net, bearer_id); > if (unlikely(!b)) > @@ -560,6 +563,7 @@ void tipc_bearer_xmit(struct net *net, u32 bearer_id, > } > } > rcu_read_unlock(); > + preempt_enable(); > } > > /* tipc_bearer_bc_xmit() - broadcast buffers to all destinations > @@ -574,6 +578,7 @@ void tipc_bearer_bc_xmit(struct net *net, u32 bearer_id, > struct sk_buff *skb, *tmp; > struct tipc_msg *hdr; > > + preempt_disable(); > rcu_read_lock(); > b = bearer_get(net, bearer_id); > if (unlikely(!b || !test_bit(0, &b->up))) > @@ -591,6 +596,7 @@ void tipc_bearer_bc_xmit(struct net *net, u32 bearer_id, > b->media->send_msg(net, skb, b, dst); > } > rcu_read_unlock(); > + preempt_enable(); > } > > /** > This is wrong, see my patch instead. https://patchwork.ozlabs.org/project/netdev/patch/20200521182958.163436-1-edumazet@google.com/ Thanks.
diff --git a/net/tipc/bearer.c b/net/tipc/bearer.c index 34ca7b789eba..e5cf91665881 100644 --- a/net/tipc/bearer.c +++ b/net/tipc/bearer.c @@ -516,6 +516,7 @@ void tipc_bearer_xmit_skb(struct net *net, u32 bearer_id, struct tipc_msg *hdr = buf_msg(skb); struct tipc_bearer *b; + preempt_disable(); rcu_read_lock(); b = bearer_get(net, bearer_id); if (likely(b && (test_bit(0, &b->up) || msg_is_reset(hdr)))) { @@ -528,6 +529,7 @@ void tipc_bearer_xmit_skb(struct net *net, u32 bearer_id, kfree_skb(skb); } rcu_read_unlock(); + preempt_enable(); } /* tipc_bearer_xmit() -send buffer to destination over bearer @@ -543,6 +545,7 @@ void tipc_bearer_xmit(struct net *net, u32 bearer_id, if (skb_queue_empty(xmitq)) return; + preempt_disable(); rcu_read_lock(); b = bearer_get(net, bearer_id); if (unlikely(!b)) @@ -560,6 +563,7 @@ void tipc_bearer_xmit(struct net *net, u32 bearer_id, } } rcu_read_unlock(); + preempt_enable(); } /* tipc_bearer_bc_xmit() - broadcast buffers to all destinations @@ -574,6 +578,7 @@ void tipc_bearer_bc_xmit(struct net *net, u32 bearer_id, struct sk_buff *skb, *tmp; struct tipc_msg *hdr; + preempt_disable(); rcu_read_lock(); b = bearer_get(net, bearer_id); if (unlikely(!b || !test_bit(0, &b->up))) @@ -591,6 +596,7 @@ void tipc_bearer_bc_xmit(struct net *net, u32 bearer_id, b->media->send_msg(net, skb, b, dst); } rcu_read_unlock(); + preempt_enable(); } /**
syzbot is reporting that tipc_udp_send_msg() is calling dst_cache_get() without preemption disabled [1]. Since b->media->send_msg() is called with RCU lock already held, we can also disable preemption at that point. [1] https://syzkaller.appspot.com/bug?id=dc6352b92862eb79373fe03fdf9af5928753e057 Reported-by: syzbot+1a68504d96cd17b33a05@syzkaller.appspotmail.com Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> --- net/tipc/bearer.c | 6 ++++++ 1 file changed, 6 insertions(+)