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

[Pavel Tikhomirov]

Looks good.

On 9/3/20 7:18 PM, Valeriy Vdovin wrote:
> 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
> 

Reviewed-by: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>

> 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 */
> 

-- 
Best regards, Tikhomirov Pavel
Software Developer, Virtuozzo.