diff options
| author | David Howells <dhowells@redhat.com> | 2020-04-28 21:27:48 +0100 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-04-28 14:37:40 -0700 |
| commit | dd7bc8158b413e0b580c491e8bd18cb91057c7c2 (patch) | |
| tree | c50f4a1e9fc7769c7f5c6b7bf0d4b1ab7085bf18 | |
| parent | edb98d162418e90d6d2c1cec42e09be0375cfd88 (diff) | |
| download | lwn-dd7bc8158b413e0b580c491e8bd18cb91057c7c2.tar.gz lwn-dd7bc8158b413e0b580c491e8bd18cb91057c7c2.zip | |
Fix use after free in get_tree_bdev()
Commit 6fcf0c72e4b9, a fix to get_tree_bdev() put a missing blkdev_put() in
the wrong place, before a warnf() that displays the bdev under
consideration rather after it.
This results in a silent lockup in printk("%pg") called via warnf() from
get_tree_bdev() under some circumstances when there's a race with the
blockdev being frozen. This can be caused by xfstests/tests/generic/085 in
combination with Lukas Czerner's ext4 mount API conversion patchset. It
looks like it ought to occur with other users of get_tree_bdev() such as
XFS, but apparently doesn't.
Fix this by switching the order of the lines.
Fixes: 6fcf0c72e4b9 ("vfs: add missing blkdev_put() in get_tree_bdev()")
Reported-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Ian Kent <raven@themaw.net>
cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | fs/super.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/super.c b/fs/super.c index cd352530eca9..a288cd60d2ae 100644 --- a/fs/super.c +++ b/fs/super.c @@ -1302,8 +1302,8 @@ int get_tree_bdev(struct fs_context *fc, mutex_lock(&bdev->bd_fsfreeze_mutex); if (bdev->bd_fsfreeze_count > 0) { mutex_unlock(&bdev->bd_fsfreeze_mutex); - blkdev_put(bdev, mode); warnf(fc, "%pg: Can't mount, blockdev is frozen", bdev); + blkdev_put(bdev, mode); return -EBUSY; } |