linux-kernel - Re: [PATCH] kernfs: move return value check after kmalloc()

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-id: <162156769760.19062.15467223033723371296@noble.neil.brown.name>
Date:   Fri, 21 May 2021 13:28:17 +1000
From:   "NeilBrown" <neilb@...e.de>
To:     "Austin Kim" <austindh.kim@...il.com>
Cc:     gregkh@...uxfoundation.org, tj@...nel.org,
        linux-kernel@...r.kernel.org, austin.kim@....com,
        austindh.kim@...il.com
Subject: Re: [PATCH] kernfs: move return value check after kmalloc()

On Fri, 21 May 2021, Austin Kim wrote:
> With 414985ae23c0 ("sysfs, kernfs: move file core code to fs/kernfs/file.c"),
> 'return -ENOMEM' is executed when kmalloc() returns NULL.
> 
> Since 'commit 4ef67a8c95f3 ("sysfs/kernfs: make read requests on pre-alloc
> files use the buffer.")', 'return -ENOMEM' statement is not properly located.
> 
> Fix it by moving 'return -ENOMEM' after return from kmalloc().

I don't think there is anything to "fix" here.  The current code is
correct.
The difference between the current code and your new code is purely a
difference in style.  I don't object to your change, but only if it is
presented as a style improvement.  It is not a code fix.

NeilBrown


> 
> Fixes: 4ef67a8c95f3 ("sysfs/kernfs: make read requests on pre-alloc files use the buffer.")
> Signed-off-by: Austin Kim <austindh.kim@...il.com>
> ---
>  fs/kernfs/file.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c
> index c75719312147..c5e2429af836 100644
> --- a/fs/kernfs/file.c
> +++ b/fs/kernfs/file.c
> @@ -191,10 +191,11 @@ static ssize_t kernfs_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
>  	buf = of->prealloc_buf;
>  	if (buf)
>  		mutex_lock(&of->prealloc_mutex);
> -	else
> +	else {
>  		buf = kmalloc(len, GFP_KERNEL);
> -	if (!buf)
> -		return -ENOMEM;
> +		if (!buf)
> +			return -ENOMEM;
> +	}
>  
>  	/*
>  	 * @of->mutex nests outside active ref and is used both to ensure that
> -- 
> 2.20.1
> 
>