Received-SPF: pass (google.com: domain of linux-kernel+bounces-284-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45e3:2400::1 as permitted sender) client-ip=2604:1380:45e3:2400::1;
Date: Thu, 14 Dec 2023 16:24:16 -0800
From: Ira Weiny <ira.weiny@intel.com>
To: Dinghao Liu <dinghao.liu@zju.edu.cn>
CC: Dan Williams <dan.j.williams@intel.com>, Vishal Verma
	<vishal.l.verma@intel.com>, Dave Jiang <dave.jiang@intel.com>, Ira Weiny
	<ira.weiny@intel.com>, <nvdimm@lists.linux.dev>,
	<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] [v2] nvdimm-btt: fix several memleaks
Message-ID: <657b9cb088175_27db80294d2@iweiny-mobl.notmuch>
References: <20231210085817.30161-1-dinghao.liu@zju.edu.cn>
Content-Type: text/plain; charset="us-ascii"
Content-Disposition: inline
In-Reply-To: <20231210085817.30161-1-dinghao.liu@zju.edu.cn>
Precedence: bulk
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?5Lt2N3Kq8x1mpSImOeWEqNkF4SUZYnfMlNe7x60qo04Eu4Ek4PgD7H5hHwb8?=
 =?us-ascii?Q?YIFICl3lrxNYXc+MI4ASxQZe78AT8S0sNG6XWzoYKLk/79QPF2xaMsO7IjLx?=
 =?us-ascii?Q?SDDty9PmgYYwcy32etHJ7hfcxdjtT+DtAzAhzzbCfAwjqQov9caiIBmA/nCi?=
 =?us-ascii?Q?4SgjT/J9gDC7GxkbhIbNuK9WuNAUiSE7ShqlM1x0BPvtiY172/QpcGUyJW65?=
 =?us-ascii?Q?nOJVbz6z5RJ4WIn8cNsRNCeLuPoz/dhlqjmW8wj5oZF+RlJDWVOp75sRi5HD?=
 =?us-ascii?Q?NecshvPs5i4OvfTFsGvq3n+1g/qFXGMGeHMQcyWGib1NUbIuhhmGNbQD9ohW?=
 =?us-ascii?Q?49MY40suyBU4VEi59U4FcSk+8WptN5J1z1pGfIZZj6DUO1HjRiloI2l1im6y?=
 =?us-ascii?Q?NU26OmUVgh3aqjvvZcMhdyDv9D9C7Iev0/pHkvC2lYoO/iDN94A0IRsUYL87?=
 =?us-ascii?Q?lgByHc4EkgAC2SHbr8z4uxsevBI1npTtwodD1d8e+tAiTA71p9Zqq/mIfUQF?=
 =?us-ascii?Q?LUPLd4YgF+brZTmsr60UfXfiKEuPm3tp2mksfNWTe3jpL63yEZUJ2OK9B0qH?=
 =?us-ascii?Q?j78wYPLT6bBIVapc2fvFBnr0Lq9OOgdwGS7N1wOFsQBDbuTyo9ky4E00kIoo?=
 =?us-ascii?Q?ERjHcavhBWjaMWeF14hfhVFLu9VogOgUJCB2x61s8+RwPC6+xv4n0ebB7YG/?=
 =?us-ascii?Q?/YoSMxU08/lo+X17bcJsBtwj3snSz4H+sTHbnM64WexZP/PlqSthKnukp3uy?=
 =?us-ascii?Q?Q0iV5PxGRVKsInLCCGbDgL32z/euv+CMUthHhlItL/EwWc8fMiZHkPht6Edd?=
 =?us-ascii?Q?Q1iFDMIdJyd979eNtgbiJ/lWXpsw3GQC7pRxRSeqsFAqYVC35T6/iHIK3USY?=
 =?us-ascii?Q?22eCPNdFh4UkQPCtnme2ATVcpPC00Oaue4TJaVgxV7ZCCwUEcfSJv8ynTAoO?=
 =?us-ascii?Q?7CBXfQK6Meijkrmf3LLzuuiD4T4cqHvIOJZ5/nr76wUB3izpWIQe7Sfr7386?=
 =?us-ascii?Q?koYw7afIhMkTaT1W3rUwZuGiKw3v/oKCD/giphuAm97alhOYjpe62qqll5dh?=
 =?us-ascii?Q?MSRitDQNUqXSDlp8YWvCyH1MglIVjTiyO/tCb+CP4Y0W5ITYwURH3aBmljPk?=
 =?us-ascii?Q?2HbXJNarCLgoPRYpRuLvdEW75UFTNNIgd0hJzcPjWV+Cizbz0NEGYbJP/qhU?=
 =?us-ascii?Q?8pTTCjzjh05NulM/tYNTdQcUQVMbvmJdZiw7ymi8YS2AaWw1alptvFKjJi0N?=
 =?us-ascii?Q?GuYHCKc6cY5VQxZYrQm9Gi2h6thuWwmvi0TkXqxNUsfe1OJc7wpJywjJnCf9?=
 =?us-ascii?Q?EBtK9A/VWblSKYDGQdAQO6UwJjgnRbMCeu6RDpDwgBVkJNa8tlw0DTQ4xfq8?=
 =?us-ascii?Q?joP3i52UoMoAtV+GExHonQ8nGjjZAhureTMPQCkmeWmUZ7MdkxbtYii/scxV?=
 =?us-ascii?Q?REx7THLt9enTpp4kjl9czX1HPx7iamyiikjtbw6a3y692/x80V5Ng+0mPjHv?=
 =?us-ascii?Q?Vncrr+agxcK2gTGM5HMJYTo2wVzGA+dJDOLk8B+ZzOvxRz5z7PMoFXR6I+ji?=
 =?us-ascii?Q?89AuCprL4m1L2p30lUwrlJ6ZA6pQSYDQzSPbdK3Q?=
X-MS-Exchange-CrossTenant-Network-Message-Id: cd410ae8-676d-4ff4-0c08-08dbfd042e4a
X-MS-Exchange-CrossTenant-AuthSource: SA1PR11MB6733.namprd11.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 15 Dec 2023 00:24:20.3499
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 46c98d88-e344-4ed4-8496-4ed7712e255d
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: bQmEsbJFcgRX/wm1IFmaGpikQW3dyqkXCs1NvKYyg6WxnOE4jyK873gDkjRI7WF1c9Q6P7Fyn5bY8glRAeXlYA==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS0PR11MB8049
X-OriginatorOrg: intel.com

Dinghao Liu wrote:
> Resources allocated by kcalloc() in btt_freelist_init(),
> btt_rtt_init(), and btt_maplocks_init() are not correctly
> released in their callers when an error happens. For
> example, when an error happens in btt_freelist_init(), its
> caller discover_arenas() will directly free arena, which makes
> arena->freelist a leaked memory. Fix these memleaks by using
> devm_kcalloc() to make the memory auto-freed on driver detach.

Thanks for this work!

> 
> Fixes: 5212e11fde4d ("nd_btt: atomic sector updates")
> Signed-off-by: Dinghao Liu <dinghao.liu@zju.edu.cn>
> ---
> 
> Changelog:
> 
> v2: -Use devm_kcalloc() to fix the memleaks.
>     -Fix the potential leaked memory in btt_rtt_init()
>      and btt_maplocks_init().
> ---
>  drivers/nvdimm/btt.c | 35 ++++++++++++++++-------------------
>  1 file changed, 16 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/nvdimm/btt.c b/drivers/nvdimm/btt.c
> index d5593b0dc700..c55231f42617 100644
> --- a/drivers/nvdimm/btt.c
> +++ b/drivers/nvdimm/btt.c
> @@ -531,13 +531,13 @@ static int arena_clear_freelist_error(struct arena_info *arena, u32 lane)
>  	return ret;
>  }
>  
> -static int btt_freelist_init(struct arena_info *arena)
> +static int btt_freelist_init(struct device *dev, struct arena_info *arena)

Both struct arena_info and struct btt contain references to struct nd_btt
which is the device you are passing down this call stack.

Just use the device in the arena/btt rather than passing a device
structure.  That makes the code easier to read and ensures that the device
associated with this arena or btt is used.

>  {
>  	int new, ret;
>  	struct log_entry log_new;
>  	u32 i, map_entry, log_oldmap, log_newmap;
>  
> -	arena->freelist = kcalloc(arena->nfree, sizeof(struct free_entry),
> +	arena->freelist = devm_kcalloc(dev, arena->nfree, sizeof(struct free_entry),

	... devm_kcalloc(&arena->nd_btt.dev, ...)

>  					GFP_KERNEL);
>  	if (!arena->freelist)
>  		return -ENOMEM;
> @@ -718,20 +718,20 @@ static int log_set_indices(struct arena_info *arena)
>  	return 0;
>  }
>  
> -static int btt_rtt_init(struct arena_info *arena)
> +static int btt_rtt_init(struct device *dev, struct arena_info *arena)
>  {
> -	arena->rtt = kcalloc(arena->nfree, sizeof(u32), GFP_KERNEL);
> +	arena->rtt = devm_kcalloc(dev, arena->nfree, sizeof(u32), GFP_KERNEL);
>  	if (arena->rtt == NULL)
>  		return -ENOMEM;
>  
>  	return 0;
>  }
>  
> -static int btt_maplocks_init(struct arena_info *arena)
> +static int btt_maplocks_init(struct device *dev, struct arena_info *arena)
>  {
>  	u32 i;
>  
> -	arena->map_locks = kcalloc(arena->nfree, sizeof(struct aligned_lock),
> +	arena->map_locks = devm_kcalloc(dev, arena->nfree, sizeof(struct aligned_lock),
>  				GFP_KERNEL);
>  	if (!arena->map_locks)
>  		return -ENOMEM;
> @@ -805,9 +805,6 @@ static void free_arenas(struct btt *btt)
>  
>  	list_for_each_entry_safe(arena, next, &btt->arena_list, list) {
>  		list_del(&arena->list);
> -		kfree(arena->rtt);
> -		kfree(arena->map_locks);
> -		kfree(arena->freelist);

This does not quite work.

free_arenas() is used in the error paths of create_arenas() and
discover_arenas().  In those cases devm_kfree() is probably a better way
to clean up this.

However...

>  		debugfs_remove_recursive(arena->debugfs_dir);
>  		kfree(arena);

Why can't arena be allocated with devm_*?

We need to change this up a bit more to handle the error path vs regular
device shutdown free (automatic devm frees).

Ira