From: Al Viro <viro@zeniv.linux.org.uk>
To: syzbot <syzbot+e24baf53dc389927a7c3@syzkaller.appspotmail.com>
Cc: davem@davemloft.net, kuba@kernel.org,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
maz@kernel.org, netdev@vger.kernel.org,
syzkaller-bugs@googlegroups.com
Subject: Re: general protection fault in sock_close
Date: Mon, 31 Aug 2020 21:03:28 +0100 [thread overview]
Message-ID: <20200831200328.GX1236603@ZenIV.linux.org.uk> (raw)
In-Reply-To: <000000000000dc862405ae31ae9b@google.com>
On Mon, Aug 31, 2020 at 12:48:13PM -0700, syzbot wrote:
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: 15bc20c6 Merge tag 'tty-5.9-rc3' of git://git.kernel.org/p..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=16a85669900000
> kernel config: https://syzkaller.appspot.com/x/.config?x=891ca5711a9f1650
> dashboard link: https://syzkaller.appspot.com/bug?extid=e24baf53dc389927a7c3
> compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=127d3c99900000
> The issue was bisected to:
>
> commit a9ed4a6560b8562b7e2e2bed9527e88001f7b682
> Author: Marc Zyngier <maz@kernel.org>
> Date: Wed Aug 19 16:12:17 2020 +0000
>
> epoll: Keep a reference on files added to the check list
All of those are essentially duplicates.
The minimal fix is below; I'm not happy with it long-term, but I'm still
digging through the eventpoll locking, and there's a good chance that this
is the least intrusive variant for -stable. Folks, could you check if the
following patch fixes those suckers? Again, all reports bisected to that
commit are essentially the same.
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index e0decff22ae2..8107e06d7f6f 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -1995,9 +1995,9 @@ static int ep_loop_check_proc(void *priv, void *cookie, int call_nests)
* during ep_insert().
*/
if (list_empty(&epi->ffd.file->f_tfile_llink)) {
- get_file(epi->ffd.file);
- list_add(&epi->ffd.file->f_tfile_llink,
- &tfile_check_list);
+ if (get_file_rcu(epi->ffd.file))
+ list_add(&epi->ffd.file->f_tfile_llink,
+ &tfile_check_list);
}
}
}
next prev parent reply other threads:[~2020-08-31 20:03 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-31 19:48 general protection fault in sock_close syzbot
2020-08-31 20:03 ` Al Viro [this message]
2020-08-31 20:39 ` Marc Zyngier
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