linux-ext4 - Re: [PATCH] e2fsprogs: allow 0-length xattr values in e2fsck

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Date:	Fri, 12 Apr 2013 12:02:37 -0500
From:	Eric Sandeen <sandeen@...hat.com>
To:	ext4 development <linux-ext4@...r.kernel.org>
CC:	David Shaw <dshaw@...berwocky.com>,
	Harald Reindl <h.reindl@...lounge.net>
Subject: Re: [PATCH] e2fsprogs: allow 0-length xattr values in e2fsck

On 4/7/13 1:42 PM, Eric Sandeen wrote:
> e2fsck thinks that this:
> 
> # touch mnt/testfile1
> # setfattr -n "user.test" mnt/testfile1
> 
> results in a filesystem with corruption:
> 
> Pass 1: Checking inodes, blocks, and sizes
> Extended attribute in inode 12 has a value size (0) which is invalid
> Clear? yes
> 
> but as far as I can tell, there is absolutely nothing wrong with
> a 0-length value on an extended attribute.  Just remove the check.
> 
> Reported-by: David Shaw <dshaw@...berwocky.com>
> Reported-by: Harald Reindl <h.reindl@...lounge.net>
> Addresses-Red-Hat-Bugzilla: #557959
> Signed-off-by: Eric Sandeen <sandeen@...hat.com>

Ted, just a ping on this.  I know there's been a lot going on,so
wasn't sure if you missed it, or if it's just saved for later.

Thanks,
-Eric

> ---
> 
> Strange that this has been in e2fsck since 2005; apologies to 
> David in particular for not addressing the bug he filed much sooner,
> I had assumed that this was some strange corruption, not a simple
> logic error / change.
> 
> diff --git a/e2fsck/pass1.c b/e2fsck/pass1.c
> index a20b57b..94df36d 100644
> --- a/e2fsck/pass1.c
> +++ b/e2fsck/pass1.c
> @@ -307,7 +307,7 @@ static void check_ea_in_inode(e2fsck_t ctx, struct problem_context *pctx)
>  		remain -= EXT2_EXT_ATTR_SIZE(entry->e_name_len);
>  
>  		/* check value size */
> -		if (entry->e_value_size == 0 || entry->e_value_size > remain) {
> +		if (entry->e_value_size > remain) {
>  			pctx->num = entry->e_value_size;
>  			problem = PR_1_ATTR_VALUE_SIZE;
>  			goto fix;
> 
> --
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