Re: [PATCH 6.6/6.9] ext4: avoid ptr null pointer dereference

[Greg KH <gregkh@linuxfoundation.org>]

On Tue, Jul 16, 2024 at 05:29:29PM +0800, libaokun@huaweicloud.com wrote:
> From: Baokun Li <libaokun1@huawei.com>
> 
> When commit 13df4d44a3aa ("ext4: fix slab-out-of-bounds in
> ext4_mb_find_good_group_avg_frag_lists()") was backported to stable, the
> commit f536808adcc3 ("ext4: refactor out ext4_generic_attr_store()") that
> uniformly determines if the ptr is null is not merged in, so it needs to
> be judged whether ptr is null or not in each case of the switch, otherwise
> null pointer dereferencing may occur.
> 
> Signed-off-by: Baokun Li <libaokun1@huawei.com>
> ---
>  fs/ext4/sysfs.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/fs/ext4/sysfs.c b/fs/ext4/sysfs.c
> index 63cbda3700ea..d65dccb44ed5 100644
> --- a/fs/ext4/sysfs.c
> +++ b/fs/ext4/sysfs.c
> @@ -473,6 +473,8 @@ static ssize_t ext4_attr_store(struct kobject *kobj,
>  			*((unsigned int *) ptr) = t;
>  		return len;
>  	case attr_clusters_in_group:
> +		if (!ptr)
> +			return 0;
>  		ret = kstrtouint(skip_spaces(buf), 0, &t);
>  		if (ret)
>  			return ret;
> -- 
> 2.39.2
> 
> 

Now queued up, thanks for the fix!

greg k-h