This is a note to let you know that I've just added the patch titled
ext4: Fix buffer double free in ext4_alloc_branch()
to the 3.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ext4-fix-buffer-double-free-in-ext4_alloc_branch.patch
and it can be found in the queue-3.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From c5c7b8ddfbf8cb3b2291e515a34ab1b8982f5a2d Mon Sep 17 00:00:00 2001
From: Jan Kara <jack@xxxxxxx>
Date: Sun, 15 Jun 2014 23:46:28 -0400
Subject: ext4: Fix buffer double free in ext4_alloc_branch()
From: Jan Kara <jack@xxxxxxx>
commit c5c7b8ddfbf8cb3b2291e515a34ab1b8982f5a2d upstream.
Error recovery in ext4_alloc_branch() calls ext4_forget() even for
buffer corresponding to indirect block it did not allocate. This leads
to brelse() being called twice for that buffer (once from ext4_forget()
and once from cleanup in ext4_ind_map_blocks()) leading to buffer use
count misaccounting. Eventually (but often much later because there
are other users of the buffer) we will see messages like:
VFS: brelse: Trying to free free buffer
Another manifestation of this problem is an error:
JBD2 unexpected failure: jbd2_journal_revoke: !buffer_revoked(bh);
inconsistent data on disk
The fix is easy - don't forget buffer we did not allocate. Also add an
explanatory comment because the indexing at ext4_alloc_branch() is
somewhat subtle.
Signed-off-by: Jan Kara <jack@xxxxxxx>
Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/ext4/indirect.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
--- a/fs/ext4/indirect.c
+++ b/fs/ext4/indirect.c
@@ -389,7 +389,13 @@ static int ext4_alloc_branch(handle_t *h
return 0;
failed:
for (; i >= 0; i--) {
- if (i != indirect_blks && branch[i].bh)
+ /*
+ * We want to ext4_forget() only freshly allocated indirect
+ * blocks. Buffer for new_blocks[i-1] is at branch[i].bh and
+ * buffer at branch[0].bh is indirect block / inode already
+ * existing before ext4_alloc_branch() was called.
+ */
+ if (i > 0 && i != indirect_blks && branch[i].bh)
ext4_forget(handle, 1, inode, branch[i].bh,
branch[i].bh->b_blocknr);
ext4_free_blocks(handle, inode, NULL, new_blocks[i],
Patches currently in stable-queue which might be from jack@xxxxxxx are
queue-3.14/ext4-fix-buffer-double-free-in-ext4_alloc_branch.patch
queue-3.14/ext4-fix-hole-punching-for-files-with-indirect-blocks.patch
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