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From: Al Viro <viro@zeniv.linux.org.uk>
To: syzbot <syzbot+ce18da013d76d837144d@syzkaller.appspotmail.com>
Cc: davem@davemloft.net, gregkh@linuxfoundation.org,
	kgraul@linux.ibm.com, linux-kernel@vger.kernel.org,
	netdev@vger.kernel.org, stranche@codeaurora.org,
	syzkaller-bugs@googlegroups.com
Subject: Re: WARNING in csum_and_copy_to_iter
Date: Sat, 24 Nov 2018 20:03:57 +0000	[thread overview]
Message-ID: <20181124200357.GC2217@ZenIV.linux.org.uk> (raw)
In-Reply-To: <0000000000001ecaa1057b6e4489@google.com>

On Sat, Nov 24, 2018 at 11:40:03AM -0800, syzbot wrote:
> Hello,
> 
> syzbot found the following crash on:
> 
> HEAD commit:    edeca3a769ad Merge tag 'sound-4.20-rc4' of git://git.kerne..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=12bee26d400000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=73e2bc0cb6463446
> dashboard link: https://syzkaller.appspot.com/bug?extid=ce18da013d76d837144d
> compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=15ccd1f5400000
> 
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+ce18da013d76d837144d@syzkaller.appspotmail.com

Caused by commit 95506588d2c1d72ca29adef8ae9bf771bcfb4ced
Author: Slavomir Kaslev <kaslevs@vmware.com>
Date:   Fri Nov 16 11:27:53 2018 +0200

    socket: do a generic_file_splice_read when proto_ops has no splice_read

exposing all ->recvmsg() instances to pipe-backed iov_iter as possible destination.
It's not all that hard to fix (I'll probably have a candidate patch by tonight,
it's just a matter of adding the only missing primitive), but... shouldn't that
patch have sat in -next for at least some testing first?  Because it's very
easy to reproduce - splice from e.g. UDP socket will step into it.  Sure, the
sky is not falling (unless you set panic-on-WARN, that is); the damn thing
would've failed anyway, but...

  reply	other threads:[~2018-11-24 20:04 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-24 19:40 WARNING in csum_and_copy_to_iter syzbot
2018-11-24 20:03 ` Al Viro [this message]
2018-11-24 21:20   ` Slavomir Kaslev
2018-11-24 21:44     ` Al Viro
2018-11-25  1:51       ` Al Viro
2018-11-26 11:46         ` Slavomir Kaslev
2023-11-24 10:30 ` [syzbot] syzbot

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