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| author | Al Viro <viro@zeniv.linux.org.uk> | 2020-04-27 10:26:22 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-05-02 17:26:01 +0200 |
| commit | fa87bf609aa173b5dce91d23cd3dcebd9e846124 (patch) | |
| tree | 1328bd9e2b49c3553662e564e27cd01a8fb3e236 | |
| parent | 38faccf5f918330394a33ed8266f98b43525869b (diff) | |
| download | linux-stable-fa87bf609aa173b5dce91d23cd3dcebd9e846124.tar.gz linux-stable-fa87bf609aa173b5dce91d23cd3dcebd9e846124.tar.bz2 linux-stable-fa87bf609aa173b5dce91d23cd3dcebd9e846124.zip | |
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>
| -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 53d411a371ce..7910ae91f17e 100644 --- a/fs/pnode.c +++ b/fs/pnode.c @@ -266,14 +266,13 @@ static int propagate_one(struct mount *m) if (IS_ERR(child)) return PTR_ERR(child); child->mnt.mnt_flags &= ~MNT_LOCKED; + 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); } |