diff options
| author | Al Viro <viro@zeniv.linux.org.uk> | 2018-10-17 15:23:26 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-11-10 07:48:34 -0800 |
| commit | ddb595dfe47278fd8ff3fd171b3729ec45d51b74 (patch) | |
| tree | 323c40e9a3945a8e944388d814d4039febf6890f /fs/cachefiles | |
| parent | 33e52eb2d00582fad17177918b83a8df19958989 (diff) | |
cachefiles: fix the race between cachefiles_bury_object() and rmdir(2)
commit 169b803397499be85bdd1e3d07d6f5e3d4bd669e upstream.
the victim might've been rmdir'ed just before the lock_rename();
unlike the normal callers, we do not look the source up after the
parents are locked - we know it beforehand and just recheck that it's
still the child of what used to be its parent. Unfortunately,
the check is too weak - we don't spot a dead directory since its
->d_parent is unchanged, dentry is positive, etc. So we sail all
the way to ->rename(), with hosting filesystems _not_ expecting
to be asked renaming an rmdir'ed subdirectory.
The fix is easy, fortunately - the lock on parent is sufficient for
making IS_DEADDIR() on child safe.
Cc: stable@vger.kernel.org
Fixes: 9ae326a69004 (CacheFiles: A cache that backs onto a mounted filesystem)
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/cachefiles')
| -rw-r--r-- | fs/cachefiles/namei.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/cachefiles/namei.c b/fs/cachefiles/namei.c index 5f2f67d220fa..f6ed795f4af6 100644 --- a/fs/cachefiles/namei.c +++ b/fs/cachefiles/namei.c @@ -340,7 +340,7 @@ try_again: trap = lock_rename(cache->graveyard, dir); /* do some checks before getting the grave dentry */ - if (rep->d_parent != dir) { + if (rep->d_parent != dir || IS_DEADDIR(d_inode(rep))) { /* the entry was probably culled when we dropped the parent dir * lock */ unlock_rename(cache->graveyard, dir); |