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| author |   Andrey Ulanov <andreyu@google.com> | 2016-04-15 14:24:41 -0700 |
|---|---|---|
| committer |   Al Viro <viro@zeniv.linux.org.uk> | 2016-06-30 23:28:30 -0400 |
| commit | e06b933e6ded42384164d28a2060b7f89243b895 (patch) | |
| tree | 5dfb0149aec8be222d613391fd1e49c791d6485f /fs | |
| parent | 9p: use file_dentry() (diff) | |
| download | linux-dev-e06b933e6ded42384164d28a2060b7f89243b895.tar.xz linux-dev-e06b933e6ded42384164d28a2060b7f89243b895.zip | |
namespace: update event counter when umounting a deleted dentry
- m_start() in fs/namespace.c expects that ns->event is incremented each
time a mount added or removed from ns->list.
- umount_tree() removes items from the list but does not increment event
counter, expecting that it's done before the function is called.
- There are some codepaths that call umount_tree() without updating
"event" counter. e.g. from __detach_mounts().
- When this happens m_start may reuse a cached mount structure that no
longer belongs to ns->list (i.e. use after free which usually leads
to infinite loop).
This change fixes the above problem by incrementing global event counter
before invoking umount_tree().
Change-Id: I622c8e84dcb9fb63542372c5dbf0178ee86bb589
Cc: stable@vger.kernel.org
Signed-off-by: Andrey Ulanov <andreyu@google.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/namespace.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/fs/namespace.c b/fs/namespace.c index 4fb1691b4355..298618b88bba 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -1562,6 +1562,7 @@ void __detach_mounts(struct dentry *dentry) goto out_unlock; lock_mount_hash(); + event++; while (!hlist_empty(&mp->m_list)) { mnt = hlist_entry(mp->m_list.first, struct mount, mnt_mp_list); if (mnt->mnt.mnt_flags & MNT_UMOUNT) { |