diff options
| author | Al Viro <viro@zeniv.linux.org.uk> | 2019-01-06 17:41:29 +0100 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2019-01-17 17:52:49 +0100 |
| commit | 399504e21a10be16dd1408ba0147367d9d82a10c (patch) | |
| tree | 7762ae17e66c37d39687268eac7dd99965f2ba0a /kernel | |
| parent | Linux 5.0-rc2 (diff) | |
| download | linux-399504e21a10be16dd1408ba0147367d9d82a10c.tar.xz linux-399504e21a10be16dd1408ba0147367d9d82a10c.zip | |
fix cgroup_do_mount() handling of failure exits
same story as with last May fixes in sysfs (7b745a4e4051
"unfuck sysfs_mount()"); new_sb is left uninitialized
in case of early errors in kernfs_mount_ns() and papering
over it by treating any error from kernfs_mount_ns() as
equivalent to !new_ns ends up conflating the cases when
objects had never been transferred to a superblock with
ones when that has happened and resulting new superblock
had been dropped. Easily fixed (same way as in sysfs
case). Additionally, there's a superblock leak on
kernfs_node_dentry() failure *and* a dentry leak inside
kernfs_node_dentry() itself - the latter on probably
impossible errors, but the former not impossible to trigger
(as the matter of fact, injecting allocation failures
at that point *does* trigger it).
Cc: stable@kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/cgroup/cgroup.c | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index f31bd61c9466..503bba3c4bae 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -2033,7 +2033,7 @@ struct dentry *cgroup_do_mount(struct file_system_type *fs_type, int flags, struct cgroup_namespace *ns) { struct dentry *dentry; - bool new_sb; + bool new_sb = false; dentry = kernfs_mount(fs_type, flags, root->kf_root, magic, &new_sb); @@ -2043,6 +2043,7 @@ struct dentry *cgroup_do_mount(struct file_system_type *fs_type, int flags, */ if (!IS_ERR(dentry) && ns != &init_cgroup_ns) { struct dentry *nsdentry; + struct super_block *sb = dentry->d_sb; struct cgroup *cgrp; mutex_lock(&cgroup_mutex); @@ -2053,12 +2054,14 @@ struct dentry *cgroup_do_mount(struct file_system_type *fs_type, int flags, spin_unlock_irq(&css_set_lock); mutex_unlock(&cgroup_mutex); - nsdentry = kernfs_node_dentry(cgrp->kn, dentry->d_sb); + nsdentry = kernfs_node_dentry(cgrp->kn, sb); dput(dentry); + if (IS_ERR(nsdentry)) + deactivate_locked_super(sb); dentry = nsdentry; } - if (IS_ERR(dentry) || !new_sb) + if (!new_sb) cgroup_put(&root->cgrp); return dentry; |