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authorAndrey Ulanov <andreyu@google.com>2016-04-15 14:24:41 -0700
committerAl Viro <viro@zeniv.linux.org.uk>2016-06-30 23:28:30 -0400
commite06b933e6ded42384164d28a2060b7f89243b895 (patch)
tree5dfb0149aec8be222d613391fd1e49c791d6485f
parentb403f0e37a11f84f7ceaf40b0075499e5bcfd220 (diff)
downloadlinux-e06b933e6ded42384164d28a2060b7f89243b895.tar.gz
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>
-rw-r--r--fs/namespace.c1
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) {