On Thu, Jan 04, 2018 at 10:14:38AM -0800, Andrei Vagin wrote: > On Thu, Jan 04, 2018 at 01:01:17PM +0100, Dmitry Vyukov wrote: > > On Wed, Jan 3, 2018 at 8:37 AM, Andrei Vagin <ava...@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+e432865c29eb4c48c...@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+e432865c29eb4c48c...@syzkaller.appspotmail.com > > > > It will help syzbot understand when the bug is fixed.
This crash is no longer occurring, thanks Andrei! The Reported-by tag didn't actually make it into the commit (f428fe4a04cc), so I'll tell syzbot instead: #syz fix: rtnetlink: give a user socket to get_target_net() - Eric
