From: Al Viro <viro@ZenIV.linux.org.uk>
To: Hugh Dickins <hughd@google.com>
Cc: David Rientjes <rientjes@google.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Fengguang Wu <fengguang.wu@intel.com>,
Li Zefan <lizefan@huawei.com>, Aristeu Rozanski <aris@redhat.com>,
Tejun Heo <tj@kernel.org>, Mimi Zohar <zohar@linux.vnet.ibm.com>,
James Morris <jmorris@namei.org>,
Dmitry Kasatkin <dmitry.kasatkin@intel.com>,
linux-security-module@vger.kernel.org,
linux-kernel@vger.kernel.org,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Subject: Re: [patch for-3.7] fs, xattr: fix bug when removing a name not in xattr list
Date: Thu, 18 Oct 2012 05:33:33 +0100 [thread overview]
Message-ID: <20121018043333.GF2616@ZenIV.linux.org.uk> (raw)
In-Reply-To: <alpine.LSU.2.00.1210172052420.20979@eggly.anvils>
On Wed, Oct 17, 2012 at 08:55:49PM -0700, Hugh Dickins wrote:
> On Wed, 17 Oct 2012, David Rientjes wrote:
>
> > Commit 38f38657444d ("xattr: extract simple_xattr code from tmpfs") moved
> > some code from tmpfs but introduced a subtle bug along the way.
> >
> > If the name passed to simple_xattr_remove() does not exist in the list of
> > xattrs, then it is possible to call kfree(new_xattr) when new_xattr is
> > actually initialized to itself on the stack via uninitialized_var().
> >
> > This causes a BUG() since the memory was not allocated via the slab
> > allocator and was not bypassed through to the page allocator because it
> > was too large.
> >
> > Initialize the local variable to NULL so the kfree() never takes place.
> >
> > Reported-by: Fengguang Wu <fengguang.wu@intel.com>
> > Signed-off-by: David Rientjes <rientjes@google.com>
>
> Acked-by: Hugh Dickins <hughd@google.com>
>
> Thank you both: a fine example of the danger of uninitialized_var()!
Applied.
next prev parent reply other threads:[~2012-10-18 4:33 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-18 2:43 [ima_inode_post_setattr] kernel BUG at mm/slub.c:3479! Fengguang Wu
2012-10-18 3:07 ` Mimi Zohar
2012-10-18 3:07 ` David Rientjes
2012-10-18 3:41 ` [patch for-3.7] fs, xattr: fix bug when removing a name not in xattr list David Rientjes
2012-10-18 3:55 ` Hugh Dickins
2012-10-18 4:33 ` Al Viro [this message]
2012-10-18 12:43 ` Hillf Danton
2012-10-18 13:43 ` Aristeu Rozanski
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