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

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Date:	Sun, 07 Apr 2013 13:42:18 -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: [PATCH] e2fsprogs: allow 0-length xattr values in e2fsck

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>
---

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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