linux-kernel - Re: [PATCH] reiserfs: check kstrdup failure

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Message-ID: <20160525154309.GC18591@quack2.suse.cz>
Date:	Wed, 25 May 2016 17:43:09 +0200
From:	Jan Kara <jack@...e.cz>
To:	Mikulas Patocka <mikulas@...bright.com>
Cc:	reiserfs-devel@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH] reiserfs: check kstrdup failure

On Tue 24-05-16 22:51:27, Mikulas Patocka wrote:
> Check out-of-memory failure of the kstrdup option. Note that the argument
> "arg" may be NULL (in that case kstrup returns NULL), so out of memory
> condition happened if arg was non-NULL and kstrdup returned NULL.
> 
> The patch also changes the call to replace_mount_options - if we didn't
> pass any filesystem-specific options, we don't call replace_mount_options
> (thus we don't erase existing reported options).
> 
> Note that to properly report options after remount, the reiserfs 
> filesystem should implement the show_options method. Without the 
> show_options method, options changed with remount replace existing 
> options.
> 
> Signed-off-by: Mikulas Patocka <mpatocka@...hat.com>

OK, makes sense. I've added the patch to my tree and will push it to Linus.
Thanks for the patch.

								Honza
> 
> ---
>  fs/reiserfs/super.c |    9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> Index: linux-4.6/fs/reiserfs/super.c
> ===================================================================
> --- linux-4.6.orig/fs/reiserfs/super.c	2016-05-19 20:59:46.000000000 +0200
> +++ linux-4.6/fs/reiserfs/super.c	2016-05-19 21:00:00.000000000 +0200
> @@ -1393,7 +1393,7 @@ static int reiserfs_remount(struct super
>  	unsigned long safe_mask = 0;
>  	unsigned int commit_max_age = (unsigned int)-1;
>  	struct reiserfs_journal *journal = SB_JOURNAL(s);
> -	char *new_opts = kstrdup(arg, GFP_KERNEL);
> +	char *new_opts;
>  	int err;
>  	char *qf_names[REISERFS_MAXQUOTAS];
>  	unsigned int qfmt = 0;
> @@ -1401,6 +1401,10 @@ static int reiserfs_remount(struct super
>  	int i;
>  #endif
>  
> +	new_opts = kstrdup(arg, GFP_KERNEL);
> +	if (arg && !new_opts)
> +		return -ENOMEM;
> +
>  	sync_filesystem(s);
>  	reiserfs_write_lock(s);
>  
> @@ -1546,7 +1550,8 @@ static int reiserfs_remount(struct super
>  	}
>  
>  out_ok_unlocked:
> -	replace_mount_options(s, new_opts);
> +	if (new_opts)
> +		replace_mount_options(s, new_opts);
>  	return 0;
>  
>  out_err_unlock:
> --
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-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR