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From: Tejun Heo <tj@kernel.org>
To: Haitao Huang <haitao.huang@linux.intel.com>
Cc: jarkko@kernel.org, dave.hansen@linux.intel.com,
	linux-kernel@vger.kernel.org, linux-sgx@vger.kernel.org,
	cgroups@vger.kernel.org, Zefan Li <lizefan.x@bytedance.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	vipinsh@google.com, kai.huang@intel.com,
	reinette.chatre@intel.com, zhiquan1.li@intel.com,
	kristen@linux.intel.com
Subject: Re: [PATCH] cgroup/misc: Fix an overflow
Date: Mon, 17 Jul 2023 08:51:39 -1000	[thread overview]
Message-ID: <ZLWNu4IeehNVO1nh@slm.duckdns.org> (raw)
In-Reply-To: <20230717184719.85523-1-haitao.huang@linux.intel.com>

On Mon, Jul 17, 2023 at 11:47:19AM -0700, Haitao Huang wrote:
> The variable 'new_usage' in misc_cg_try_charge() may overflow if it
> becomes above INT_MAX. This was observed when I implement the new SGX
> EPC cgroup[1] as a misc cgroup and test on a platform with large SGX EPC
> sizes.
> 
> Change type of new_usage to long from int and check overflow.
> -	int new_usage;
> +	long new_usage;
>  
>  	if (!(valid_type(type) && cg && READ_ONCE(misc_res_capacity[type])))
>  		return -EINVAL;
> @@ -153,10 +153,10 @@ int misc_cg_try_charge(enum misc_res_type type, struct misc_cg *cg,
>  
>  	for (i = cg; i; i = parent_misc(i)) {
>  		res = &i->res[type];
> -
>  		new_usage = atomic_long_add_return(amount, &res->usage);
>  		if (new_usage > READ_ONCE(res->max) ||
> -		    new_usage > READ_ONCE(misc_res_capacity[type])) {
> +		    new_usage > READ_ONCE(misc_res_capacity[type]) ||
> +		    new_usage < 0) {

Applying to cgroup/for-6.6 (as none of the current users are affected by
this) but I think the right thing to do here is using explicit 64bit types
(s64 or u64) for the resource counters rather than depending on the long
width.

Thanks.

-- 
tejun

WARNING: multiple messages have this Message-ID (diff)
From: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
To: Haitao Huang <haitao.huang-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
Cc: jarkko-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org,
	dave.hansen-VuQAYsv1563Yd54FQh9/CA@public.gmane.org,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-sgx-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	Zefan Li <lizefan.x-EC8Uxl6Npydl57MIdRCFDg@public.gmane.org>,
	Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>,
	vipinsh-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org,
	kai.huang-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org,
	reinette.chatre-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org,
	zhiquan1.li-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org,
	kristen-VuQAYsv1563Yd54FQh9/CA@public.gmane.org
Subject: Re: [PATCH] cgroup/misc: Fix an overflow
Date: Mon, 17 Jul 2023 08:51:39 -1000	[thread overview]
Message-ID: <ZLWNu4IeehNVO1nh@slm.duckdns.org> (raw)
In-Reply-To: <20230717184719.85523-1-haitao.huang-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>

On Mon, Jul 17, 2023 at 11:47:19AM -0700, Haitao Huang wrote:
> The variable 'new_usage' in misc_cg_try_charge() may overflow if it
> becomes above INT_MAX. This was observed when I implement the new SGX
> EPC cgroup[1] as a misc cgroup and test on a platform with large SGX EPC
> sizes.
> 
> Change type of new_usage to long from int and check overflow.
> -	int new_usage;
> +	long new_usage;
>  
>  	if (!(valid_type(type) && cg && READ_ONCE(misc_res_capacity[type])))
>  		return -EINVAL;
> @@ -153,10 +153,10 @@ int misc_cg_try_charge(enum misc_res_type type, struct misc_cg *cg,
>  
>  	for (i = cg; i; i = parent_misc(i)) {
>  		res = &i->res[type];
> -
>  		new_usage = atomic_long_add_return(amount, &res->usage);
>  		if (new_usage > READ_ONCE(res->max) ||
> -		    new_usage > READ_ONCE(misc_res_capacity[type])) {
> +		    new_usage > READ_ONCE(misc_res_capacity[type]) ||
> +		    new_usage < 0) {

Applying to cgroup/for-6.6 (as none of the current users are affected by
this) but I think the right thing to do here is using explicit 64bit types
(s64 or u64) for the resource counters rather than depending on the long
width.

Thanks.

-- 
tejun

  reply	other threads:[~2023-07-17 18:51 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-07-17 18:47 [PATCH] cgroup/misc: Fix an overflow Haitao Huang
2023-07-17 18:51 ` Tejun Heo [this message]
2023-07-17 18:51   ` Tejun Heo
2023-07-17 18:55 ` Jarkko Sakkinen
2023-07-17 18:55   ` Jarkko Sakkinen
2023-07-17 18:57   ` Tejun Heo
2023-07-17 18:57     ` Tejun Heo
2023-07-17 19:01     ` Haitao Huang
2023-07-17 19:01       ` Haitao Huang
2023-07-17 20:19       ` Haitao Huang
2023-07-17 20:19         ` Haitao Huang
2023-07-17 20:37         ` Tejun Heo
2023-07-18  1:08           ` [PATCH 1/2] " Haitao Huang
2023-07-18  1:08             ` [PATCH 2/2] cgroup/misc: Change counters to be explicit 64bit types Haitao Huang
2023-07-18  1:08               ` Haitao Huang
2023-07-18 22:52               ` Tejun Heo
2023-07-18 22:52                 ` Tejun Heo
2023-07-21  2:48                 ` Haitao Huang
2023-07-21  2:48                   ` Haitao Huang
2023-07-21 12:02                 ` [PATCH] cgroup/misc: Store atomic64_t reads to u64 Haitao Huang
2023-07-21 12:02                   ` Haitao Huang
2023-07-21 18:10                   ` Tejun Heo
2023-07-21 18:10                     ` Tejun Heo
2023-07-18  1:11           ` [PATCH] cgroup/misc: Fix an overflow Haitao Huang
2023-07-18  1:11             ` Haitao Huang
2023-07-18 15:41           ` Jarkko Sakkinen
2023-07-18 15:41             ` Jarkko Sakkinen

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