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authorAl Viro <viro@zeniv.linux.org.uk>2019-01-06 11:41:29 -0500
committerAl Viro <viro@zeniv.linux.org.uk>2019-01-17 11:52:49 -0500
commit399504e21a10be16dd1408ba0147367d9d82a10c (patch)
tree7762ae17e66c37d39687268eac7dd99965f2ba0a /kernel/cgroup
parent1c7fc5cbc33980acd13d668f1c8f0313d6ae9fd8 (diff)
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/cgroup')
-rw-r--r--kernel/cgroup/cgroup.c9
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;