[patch] memcontrol: fix potential null deref

[patch] memcontrol: fix potential null deref

[Dan Carpenter]

There was a potential null deref introduced in:
c62b1a3b31b5 memcg: use generic percpu instead of private implementation

Signed-off-by: Dan Carpenter <error27@gmail.com>

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 7973b52..e1e0996 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3691,8 +3691,10 @@ static struct mem_cgroup *mem_cgroup_alloc(void)
 	else
 		mem = vmalloc(size);
 
-	if (mem)
-		memset(mem, 0, size);
+	if (!mem)
+		return NULL;
+
+	memset(mem, 0, size);
 	mem->stat = alloc_percpu(struct mem_cgroup_stat_cpu);
 	if (!mem->stat) {
 		if (size < PAGE_SIZE)

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Re: [patch] memcontrol: fix potential null deref

[KAMEZAWA Hiroyuki]

On Sat, 13 Mar 2010 17:56:21 +0300
Dan Carpenter <error27@gmail.com> wrote:

> There was a potential null deref introduced in:
> c62b1a3b31b5 memcg: use generic percpu instead of private implementation
> 
> Signed-off-by: Dan Carpenter <error27@gmail.com>

Thanks.
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

> 
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 7973b52..e1e0996 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -3691,8 +3691,10 @@ static struct mem_cgroup *mem_cgroup_alloc(void)
>  	else
>  		mem = vmalloc(size);
>  
> -	if (mem)
> -		memset(mem, 0, size);
> +	if (!mem)
> +		return NULL;
> +
> +	memset(mem, 0, size);
>  	mem->stat = alloc_percpu(struct mem_cgroup_stat_cpu);
>  	if (!mem->stat) {
>  		if (size < PAGE_SIZE)
> --
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