From: Al Viro <viro@ZenIV.linux.org.uk>
To: "Theodore Ts'o" <tytso@mit.edu>,
Stephen Rothwell <sfr@canb.auug.org.au>,
linux-next@vger.kernel.org, linux-kernel@vger.kernel.org,
David Howells <dhowells@redhat.com>
Subject: Re: linux-next: manual merge of the vfs tree with the ext4 tree
Date: Tue, 14 Apr 2015 18:17:43 +0100 [thread overview]
Message-ID: <20150414171743.GC889@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20150414170000.GB29810@thunk.org>
On Tue, Apr 14, 2015 at 01:00:00PM -0400, Theodore Ts'o wrote:
> > Look, either nd_get_link() points inside that page (in which case that
> > kfree() is obviously invalid), or it points at kmalloc'ed buffer. In
> > which case kfree() is correct, but WTF do you need anything _else_?
> > Such as mapped pages, etc.
>
> Yes, it's either one or the other.
>
> 1) In the case of an unencrypted symlink which is too big to fit in
> the inode, we map in the first (only) block of the symlink, and set
> the link to it.
... and that kfree() will bugger us.
> 2) In the case of an encrypted symlink, we allocate memory and decrypt
> from the first block (or the i_block[] array in the inode), and then
> release the page if necessary.
... and that should've dropped that page in ->follow_link().
> I suppose we could have gone from two struct inode_operations (for
> fast and "slow" symlinks), to four struct inodes_operations (for
> [fast, unencrypted symlinks], [fast, encrypted symlinks], [slow,
> unencrypted symlinks], and [slow, encrypted symlinks]), but it was
> simpler to use a single follow_link() and put_link() function to
> handle multiple cases.
Except that you do not handle the slow unencrypted case - you end up with
kfree() on the freshly kunmaped address.
next prev parent reply other threads:[~2015-04-14 17:17 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-14 1:30 linux-next: manual merge of the vfs tree with the ext4 tree Stephen Rothwell
2015-04-14 1:48 ` Al Viro
2015-04-14 17:00 ` Theodore Ts'o
2015-04-14 17:17 ` Al Viro [this message]
2015-04-14 21:02 ` Theodore Ts'o
2015-04-14 21:14 ` Al Viro
-- strict thread matches above, loose matches on Subject: below --
2020-01-27 22:51 Stephen Rothwell
2016-05-17 0:23 Stephen Rothwell
2016-05-17 3:16 ` Theodore Ts'o
2016-05-18 14:25 ` Arnd Bergmann
2016-05-19 1:26 ` Stephen Rothwell
2015-06-09 2:47 Stephen Rothwell
2015-05-11 0:49 Stephen Rothwell
2015-04-15 1:35 Stephen Rothwell
2015-04-13 1:48 Stephen Rothwell
2015-04-13 1:43 Stephen Rothwell
2015-04-07 4:00 Stephen Rothwell
2015-04-07 7:02 ` Christoph Hellwig
2015-04-07 7:36 ` Stephen Rothwell
2015-04-08 3:26 ` Theodore Ts'o
2015-04-14 16:18 ` Christoph Hellwig
2015-04-14 20:43 ` Theodore Ts'o
2014-05-27 2:07 Stephen Rothwell
2014-04-22 1:13 Stephen Rothwell
2012-01-06 2:54 Stephen Rothwell
2012-01-06 20:46 ` Djalal Harouni
2011-12-21 0:18 Stephen Rothwell
2011-12-21 0:43 ` Stephen Rothwell
2011-07-18 3:36 Stephen Rothwell
2011-07-25 2:38 ` Stephen Rothwell
2009-05-19 4:23 Stephen Rothwell
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