diff options
| author | Al Viro <viro@zeniv.linux.org.uk> | 2018-10-05 14:29:46 -0400 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2018-10-05 14:37:28 -0400 |
| commit | b07581d2d5add23ae163e3fbfb2fa5d36076922f (patch) | |
| tree | 1e932e63894e23c27a6c332dedda164c02e78fbd /fs | |
| parent | ffc4c92227db5699493e43eb140b4cb5904c30ff (diff) | |
| download | linux-b07581d2d5add23ae163e3fbfb2fa5d36076922f.tar.bz2 | |
cachefiles: fix the race between cachefiles_bury_object() and rmdir(2)
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>
Diffstat (limited to 'fs')
| -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 af2b17b21b94..95983c744164 100644 --- a/fs/cachefiles/namei.c +++ b/fs/cachefiles/namei.c @@ -343,7 +343,7 @@ 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); |