diff options
| author | Al Viro <viro@zeniv.linux.org.uk> | 2020-04-27 10:26:22 -0400 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2020-05-22 21:19:11 +0100 |
| commit | 42f443179444258caf10b7f4f9f4e75201150918 (patch) | |
| tree | 5019a7b39ff61c8ec55c65749d0e2f53ee27fbf4 | |
| parent | 172f22d527862eb5aa9dd767826f5d68562943db (diff) | |
| download | linux-stable-42f443179444258caf10b7f4f9f4e75201150918.tar.gz | |
propagate_one(): mnt_set_mountpoint() needs mount_lock
commit b0d3869ce9eeacbb1bbd541909beeef4126426d5 upstream.
... to protect the modification of mp->m_count done by it. Most of
the places that modify that thing also have namespace_lock held,
but not all of them can do so, so we really need mount_lock here.
Kudos to Piotr Krysiuk <piotras@gmail.com>, who'd spotted a related
bug in pivot_root(2) (fixed unnoticed in 5.3); search for other
similar turds has caught out this one.
Cc: stable@kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Piotr Krysiuk <piotras@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
| -rw-r--r-- | fs/pnode.c | 9 |
1 files changed, 4 insertions, 5 deletions
diff --git a/fs/pnode.c b/fs/pnode.c index 52e7506782cbd9..3f6281239a3610 100644 --- a/fs/pnode.c +++ b/fs/pnode.c @@ -249,14 +249,13 @@ static int propagate_one(struct mount *m) child = copy_tree(last_source, last_source->mnt.mnt_root, type); if (IS_ERR(child)) return PTR_ERR(child); + read_seqlock_excl(&mount_lock); mnt_set_mountpoint(m, mp, child); + if (m->mnt_master != dest_master) + SET_MNT_MARK(m->mnt_master); + read_sequnlock_excl(&mount_lock); last_dest = m; last_source = child; - if (m->mnt_master != dest_master) { - read_seqlock_excl(&mount_lock); - SET_MNT_MARK(m->mnt_master); - read_sequnlock_excl(&mount_lock); - } hlist_add_head(&child->mnt_hash, list); return count_mounts(m->mnt_ns, child); } |