Messages in this thread | | | Date | Thu, 4 Jan 2018 10:14:38 -0800 | From | Andrei Vagin <> | Subject | Re: general protection fault in __netlink_ns_capable |
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On Thu, Jan 04, 2018 at 01:01:17PM +0100, Dmitry Vyukov wrote: > On Wed, Jan 3, 2018 at 8:37 AM, Andrei Vagin <avagin@virtuozzo.com> wrote: > >> > Hello, > >> > > >> > syzkaller hit the following crash on > >> > 75aa5540627fdb3d8f86229776ea87f995275351 > >> > git://git.cmpxchg.org/linux-mmots.git/master > >> > compiler: gcc (GCC) 7.1.1 20170620 > >> > .config is attached > >> > Raw console output is attached. > >> > C reproducer is attached > >> > syzkaller reproducer is attached. See https://goo.gl/kgGztJ > >> > for information about syzkaller reproducers > >> > > >> > > >> > IMPORTANT: if you fix the bug, please add the following tag to the commit: > >> > Reported-by: syzbot+e432865c29eb4c48c142@syzkaller.appspotmail.com > >> > It will help syzbot understand when the bug is fixed. See footer for > >> > details. > >> > If you forward the report, please keep this part and the footer. > >> > > >> > netlink: 3 bytes leftover after parsing attributes in process > >> > `syzkaller140561'. > >> > netlink: 3 bytes leftover after parsing attributes in process > >> > `syzkaller140561'. > >> > netlink: 3 bytes leftover after parsing attributes in process > >> > `syzkaller140561'. > >> > kasan: CONFIG_KASAN_INLINE enabled > >> > kasan: GPF could be caused by NULL-ptr deref or user memory access > >> > general protection fault: 0000 [#1] SMP KASAN > >> > Dumping ftrace buffer: > >> > (ftrace buffer empty) > >> > Modules linked in: > >> > CPU: 1 PID: 3149 Comm: syzkaller140561 Not tainted 4.15.0-rc4-mm1+ #47 > >> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > >> > Google 01/01/2011 > >> > RIP: 0010:__netlink_ns_capable+0x8b/0x120 net/netlink/af_netlink.c:868 > >> > >> NETLINK_CB(skb).sk is NULL here. It looks like we have to use > >> sk_ns_capable instead of netlink_ns_capable: > >> > >> diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c > >> index c688dc564b11..408c75de52ea 100644 > >> --- a/net/core/rtnetlink.c > >> +++ b/net/core/rtnetlink.c > >> @@ -1762,7 +1762,7 @@ static struct net *get_target_net(struct sk_buff > >> *skb, int netnsid) > >> /* For now, the caller is required to have CAP_NET_ADMIN in > >> * the user namespace owning the target net ns. > >> */ > >> - if (!netlink_ns_capable(skb, net->user_ns, CAP_NET_ADMIN)) { > >> + if (!sk_ns_capable(skb->sk, net->user_ns, CAP_NET_ADMIN)) { > >> put_net(net); > >> return ERR_PTR(-EACCES); > >> } > >> > > > > get_target_net() is used twice in the code. In rtnl_getlink(), we need > > to use netlink_ns_capable(skb, ...), but in rtnl_dump_ifinfo, we need to > > use sk_ns_capable(skb->sk, ...). > > > > Pls, take a look at this patch: > > https://patchwork.ozlabs.org/patch/854896/ > > Subject: rtnetlink: give a user socket to get_target_net() > > > Please include this tag into the commit: >
I sent v2 with this tag. Sorry for inconvenience. https://patchwork.ozlabs.org/patch/855147/
> > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > > > Reported-by: syzbot+e432865c29eb4c48c142@syzkaller.appspotmail.com > > > It will help syzbot understand when the bug is fixed.
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