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From: Eric Biggers <ebiggers@kernel.org>
To: Cengiz Can <cengiz@kernel.wtf>
Cc: Eric Van Hensbergen <ericvh@gmail.com>,
	Latchesar Ionkov <lucho@ionkov.net>,
	Dominique Martinet <asmadeus@codewreck.org>,
	Christoph Hellwig <hch@lst.de>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	syzkaller-bugs@googlegroups.com, viro@zeniv.linux.org.uk,
	v9fs-developer@lists.sourceforge.net,
	syzbot <syzbot+d012ca3f813739c37c25@syzkaller.appspotmail.com>
Subject: Re: WARNING in __kernel_read
Date: Thu, 23 Jul 2020 08:51:42 -0700	[thread overview]
Message-ID: <20200723155142.GA870@sol.localdomain> (raw)
In-Reply-To: <455c6bf929ea197a7c18ba3f9e8464148b333297.camel@kernel.wtf>

Hi Cengiz,

On Thu, Jul 23, 2020 at 05:17:25PM +0300, Cengiz Can wrote:
> Hello,
> 
> I'm trying to help clean up syzkaller submissions and this caught my
> attention and I wanted to get your advice.
> 
> With commit: 6209dd9132e8ea5545cffc84483841e88ea8cc5b `kernel_read` was
> modified to use `__kernel_read` by Christoph Hellwig.
> 
> One of the syzkaller tests executes following system calls:
> 
> open("./file0", O_WRONLY|O_CREAT|O_EXCL|O_DIRECT|0x4, 000) = 5
> open("/dev/char/4:1", O_RDWR)           = 6
> mount(NULL, "./file0", "9p", 0,
> "trans=fd,rfdno=0x0000000000000005,wfdno=0x0000000000000006,"
> 
> This initiates a `__kernel_read` call from `p9_read_work` (and
> `p9_fd_read`) and since the `file->f_mode` does not contain FMODE_READ
> , a WARN_ON_ONCE is thrown.
> 
> ```
> if (WARN_ON_ONCE(!(file->f_mode & FMODE_READ)))
>          return -EINVAL;
> ```
> 
> Can you help me understand what's wrong and fix this issue? 
> Is it already being worked on?
> 

Looks like this was already fixed in linux-next by:

	commit a39c46067c845a8a2d7144836e9468b7f072343e
	Author: Christoph Hellwig <hch@lst.de>
	Date:   Fri Jul 10 10:57:22 2020 +0200

	    net/9p: validate fds in p9_fd_open

Let's tell syzbot so that it closes this bug report:

#syz fix: net/9p: validate fds in p9_fd_open

  reply	other threads:[~2020-07-23 15:51 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-13  7:03 WARNING in __kernel_read syzbot
2020-07-14 11:02 ` Christoph Hellwig
2020-07-23 14:17   ` Cengiz Can
2020-07-23 15:51     ` Eric Biggers [this message]
2021-10-06  9:33 Hao Sun
2021-10-06 12:17 ` Matthew Wilcox
2021-10-06 13:57   ` Theodore Ts'o
2021-10-06 22:10     ` Kees Cook
2021-10-12  6:21   ` Christoph Hellwig

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