[Devel] [PATCH RH7] cgroup: Fixed null pointer dereference at cgroup_mount #PSBM-107596

[Valeriy Vdovin]

At cgroup_mount new_root a call to cgroup_root_from_opts may return
early and not allocate a new cgroup root object, instead returning NULL.
In that case we should not initialize ve_owner field for cgroup root.

https://jira.sw.ru/browse/PSBM-107596

Signed-off-by: Valeriy Vdovin <valeriy.vdovin at virtuozzo.com>
---
 kernel/cgroup.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 5f311180..691505c 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1749,6 +1749,9 @@ static struct cgroupfs_root *cgroup_root_from_opts(struct cgroup_sb_opts *opts)
 		strcpy(root->name, opts->name);
 	if (opts->cpuset_clone_children)
 		set_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->top_cgroup.flags);
+
+	RCU_INIT_POINTER(root->top_cgroup.ve_owner, &ve0);
+
 	return root;
 }
 
@@ -1859,7 +1862,6 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type,
 		goto drop_modules;
 	}
 
-	RCU_INIT_POINTER(new_root->top_cgroup.ve_owner, &ve0);
 	opts.new_root = new_root;
 
 	/* Locate an existing or new sb for this hierarchy */
-- 
1.8.3.1