Re: [PATCH v2] posix_acl: fix memleak when set posix acl.

[Gao Xiang <gaoxiang25@huawei.com>]

Hi Xiaoxu,

On Tue, Nov 26, 2019 at 09:38:09PM +0800, Zhang Xiaoxu wrote:
> When set posix acl, it maybe call posix_acl_update_mode in some
> filesystem, eg. ext4. It may set acl to NULL, so, we can't free
> the acl which allocated in posix_acl_xattr_set.
> 
> Use an temp value to store the acl address for posix_acl_release.
> 
> Signed-off-by: Zhang Xiaoxu <zhangxiaoxu5@huawei.com>
> ---
>  fs/posix_acl.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/posix_acl.c b/fs/posix_acl.c
> index 84ad1c90d535..0a359d06274c 100644
> --- a/fs/posix_acl.c
> +++ b/fs/posix_acl.c
> @@ -882,7 +882,7 @@ posix_acl_xattr_set(const struct xattr_handler *handler,
>  		    const char *name, const void *value,
>  		    size_t size, int flags)
>  {
> -	struct posix_acl *acl = NULL;
> +	struct posix_acl *acl = NULL, *p = NULL;
>  	int ret;
>  
>  	if (value) {
> @@ -890,8 +890,15 @@ posix_acl_xattr_set(const struct xattr_handler *handler,
>  		if (IS_ERR(acl))
>  			return PTR_ERR(acl);
>  	}
> +
> +	/*
> +	 * when call set_posix_acl, posix_acl_update_mode may set acl
> +	 * to NULL,use temporary variables p for posix_acl_release.
> +	 */
> +	p = acl;
>  	ret = set_posix_acl(inode, handler->flags, acl);

IMO, variable acl in this function won't be affected, yes?
Am I missing something?

Thanks,
Gao Xiang

> -	posix_acl_release(acl);
> +
> +	posix_acl_release(p);
>  	return ret;
>  }
>  
> -- 
> 2.17.2
>