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From: Al Viro <viro@ZenIV.linux.org.uk>
To: Dmitry Vyukov <dvyukov@google.com>
Cc: syzbot <syzbot+75397ee3df5c70164154@syzkaller.appspotmail.com>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	syzkaller-bugs@googlegroups.com
Subject: Re: WARNING in kmem_cache_free
Date: Sun, 8 Apr 2018 06:59:13 +0100	[thread overview]
Message-ID: <20180408055900.GH30522@ZenIV.linux.org.uk> (raw)
In-Reply-To: <CACT4Y+adiXih0-jfNGHgf1kEQ2=KLY5NdX-87BTDbrQgEAHc9g@mail.gmail.com>

On Fri, Apr 06, 2018 at 03:33:36PM +0200, Dmitry Vyukov wrote:

> Interesting type of bug, I think we see this for the first time.
> 
> Al, do you see how this can happen?

putname() on something that hasn't come from getname().  Short
of reproducer, I don't see what can be done - it can be any
kind of memory corruption.  We have
        return filename_lookup(dfd, getname_flags(name, flags, empty),
                               flags, path, NULL);
with filename_lookup() hitting
        putname(name);
        return retval;
on the way out (and seeing refcount 1, at that, so it hasn't ended
up in audit context).  And object it's trying to free is not something
getname_flags() has allocated.

  parent reply	other threads:[~2018-04-08  6:00 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-06 13:24 WARNING in kmem_cache_free syzbot
2018-04-06 13:33 ` Dmitry Vyukov
2018-04-08  3:16   ` Use struct page for filename Matthew Wilcox
2018-04-08  4:42     ` Al Viro
2018-04-08  5:59   ` Al Viro [this message]
2018-04-08  6:01   ` WARNING in kmem_cache_free Matthew Wilcox
2018-04-08 10:26     ` Dmitry Vyukov
2018-04-08 11:18       ` Dmitry Vyukov
2018-04-08 15:31         ` Stephan Müller
2018-04-08 15:41           ` Dmitry Vyukov
2018-04-08 19:07             ` [PATCH] crypto: DRBG - guard uninstantion by lock Stephan Müller
2018-04-08 22:46               ` Theodore Y. Ts'o
2018-04-09  5:40                 ` Stephan Mueller
2018-04-09  7:57                   ` Dmitry Vyukov
2018-04-10 15:23                     ` Dmitry Vyukov
2018-04-10 15:35                       ` Stephan Mueller
2018-04-11 12:29                         ` Dmitry Vyukov
2018-04-11 12:59                           ` Stephan Mueller
2018-04-11 14:26                           ` Stephan Müller
2018-04-11 14:31                             ` [PATCH] crypto: drbg - set freed buffers to NULL Stephan Müller
2018-04-11 17:29                               ` Eric Biggers
2018-04-12  6:40                               ` Stephan Müller
2018-04-20 16:54                                 ` Herbert Xu
2018-04-11 17:09                             ` [PATCH] crypto: DRBG - guard uninstantion by lock Dmitry Vyukov

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