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| author | Jan Kara <jack@suse.cz> | 2014-06-15 23:46:28 -0400 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2014-06-15 23:46:28 -0400 |
| commit | c5c7b8ddfbf8cb3b2291e515a34ab1b8982f5a2d (patch) | |
| tree | 2969953563a5ed1d21570be8a9496c10f7bdcfde /fs | |
| parent | 7171511eaec5bf23fb06078f59784a3a0626b38f (diff) | |
| download | linux-c5c7b8ddfbf8cb3b2291e515a34ab1b8982f5a2d.tar.bz2 | |
ext4: Fix buffer double free in ext4_alloc_branch()
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@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/ext4/indirect.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/fs/ext4/indirect.c b/fs/ext4/indirect.c index 8a57e9fcd1b9..f85bafd474dc 100644 --- a/fs/ext4/indirect.c +++ b/fs/ext4/indirect.c @@ -389,7 +389,13 @@ static int ext4_alloc_branch(handle_t *handle, struct inode *inode, 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], |