From: Jan Kara <jack@suse.cz>
Date: Tue, 24 Feb 2009 21:13:18 +0000 (-0500)
Subject: jbd2: Avoid possible NULL dereference in jbd2_journal_begin_ordered_truncate()
X-Git-Tag: v2.6.27.20~9
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=fb05f46cabf4c96f5f8648c6a85d897ed57b1c94;p=pandora-kernel.git

jbd2: Avoid possible NULL dereference in jbd2_journal_begin_ordered_truncate()

(cherry picked from commit 7f5aa215088b817add9c71914b83650bdd49f8a9)

If we race with commit code setting i_transaction to NULL, we could
possibly dereference it.  Proper locking requires the journal pointer
(to access journal->j_list_lock), which we don't have.  So we have to
change the prototype of the function so that filesystem passes us the
journal pointer.  Also add a more detailed comment about why the
function jbd2_journal_begin_ordered_truncate() does what it does and
how it should be used.

Thanks to Dan Carpenter <error27@gmail.com> for pointing to the
suspitious code.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Acked-by: Joel Becker <joel.becker@oracle.com>
CC: linux-ext4@vger.kernel.org
CC: mfasheh@suse.de
CC: Dan Carpenter <error27@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---

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