diff options
| author | Al Viro <viro@zeniv.linux.org.uk> | 2020-04-27 10:26:22 -0400 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2020-04-27 10:37:14 -0400 |
| commit | b0d3869ce9eeacbb1bbd541909beeef4126426d5 (patch) | |
| tree | d710d97e4dfff49cea1b0267bf0bfb149e7bcd04 /fs/pnode.c | |
| parent | 3815f1be546e752327b5868af103ccdddcc4db77 (diff) | |
| download | lwn-b0d3869ce9eeacbb1bbd541909beeef4126426d5.tar.gz lwn-b0d3869ce9eeacbb1bbd541909beeef4126426d5.zip | |
propagate_one(): mnt_set_mountpoint() needs mount_lock
... 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>
Diffstat (limited to 'fs/pnode.c')
| -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 49f6d7ff2139..1106137c747a 100644 --- a/fs/pnode.c +++ b/fs/pnode.c @@ -261,14 +261,13 @@ 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); } |