Messages in this thread | | | Date | Wed, 18 Sep 2019 15:49:04 +0530 | From | Bharath Vedartham <> | Subject | Re: net/dst_cache.c: preemption bug in net/dst_cache.c |
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On Mon, Sep 09, 2019 at 05:48:25PM +0800, Xin Long wrote: > On Fri, Aug 23, 2019 at 3:58 PM Bharath Vedartham <linux.bhar@gmail.com> wrote: > > > > Hi all, > > > > I just want to bring attention to the syzbot bug [1] > > > > Even though syzbot claims the bug to be in net/tipc, I feel it is in > > net/dst_cache.c. Please correct me if I am wrong. > > > > This bug is being triggered a lot of times by syzbot since the day it > > was reported. Also given that this is core networking code, I felt it > > was important to bring this to attention. > > > > It looks like preemption needs to be disabled before using this_cpu_ptr > > or maybe we would be better of using a get_cpu_var and put_cpu_var combo > > here. > b->media->send_msg (tipc_udp_send_msg) > -> tipc_udp_xmit() -> dst_cache_get() > > send_msg() is always called under the protection of rcu_read_lock(), which > already disabled preemption. If not, there must be some unbalanced calls of > disable/enable preemption elsewhere. > > Agree that this could be a serious issue, do you have any reproducer for this? > > Thanks. Hi Xin,
Sorry for the delayed response. I do not have a reproducer for this. You can submit a patch to syzbot which can run the patch on the same system on which it found the bug.
Thank you Bharath > > > > [1] https://syzkaller.appspot.com/bug?id=dc6352b92862eb79373fe03fdf9af5928753e057 > > > > Thank you > > Bharath
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