linux-kernel - [PATCH 3.16 61/99] ext4: include terminating u32 in size of xattr entries when expanding inodes

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Message-ID: <lsq.1554212307.910334210@decadent.org.uk>
Date:   Tue, 02 Apr 2019 14:38:27 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Steve Graham" <stgraham2000@...il.com>,
        "Theodore Ts'o" <tytso@....edu>
Subject: [PATCH 3.16 61/99] ext4: include terminating u32 in size of xattr
 entries when expanding inodes

3.16.65-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Theodore Ts'o <tytso@....edu>

commit a805622a757b6d7f65def4141d29317d8e37b8a1 upstream.

In ext4_expand_extra_isize_ea(), we calculate the total size of the
xattr header, plus the xattr entries so we know how much of the
beginning part of the xattrs to move when expanding the inode extra
size.  We need to include the terminating u32 at the end of the xattr
entries, or else if there is uninitialized, non-zero bytes after the
xattr entries and before the xattr values, the list of xattr entries
won't be properly terminated.

Reported-by: Steve Graham <stgraham2000@...il.com>
Signed-off-by: Theodore Ts'o <tytso@....edu>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 fs/ext4/xattr.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -1340,7 +1340,7 @@ retry:
 	end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
 	min_offs = end - base;
 	last = entry;
-	total_ino = sizeof(struct ext4_xattr_ibody_header);
+	total_ino = sizeof(struct ext4_xattr_ibody_header) + sizeof(u32);
 
 	error = xattr_check_inode(inode, header, end);
 	if (error)