From: Jan Kara <jack@suse.cz>
Date: Mon, 11 Mar 2013 17:24:56 +0000 (-0400)
Subject: jbd2: fix use after free in jbd2_journal_dirty_metadata()
X-Git-Tag: v3.2.42~41
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e54ff8adf866ae54bff7d6292321c1f3eb886713;p=pandora-kernel.git

jbd2: fix use after free in jbd2_journal_dirty_metadata()

commit ad56edad089b56300fd13bb9eeb7d0424d978239 upstream.

jbd2_journal_dirty_metadata() didn't get a reference to journal_head it
was working with. This is OK in most of the cases since the journal head
should be attached to a transaction but in rare occasions when we are
journalling data, __ext4_journalled_writepage() can race with
jbd2_journal_invalidatepage() stripping buffers from a page and thus
journal head can be freed under hands of jbd2_journal_dirty_metadata().

Fix the problem by getting own journal head reference in
jbd2_journal_dirty_metadata() (and also in jbd2_journal_set_triggers()
which can possibly have the same issue).

Reported-by: Zheng Liu <gnehzuil.liu@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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