[PATCH] ext4: correct inline offset when handling xattrs in inode body

[PATCH] ext4: correct inline offset when handling xattrs in inode body

[Eric Whitney]

When run on a file system where the inline_data feature has been
enabled, xfstests generic/269, generic/270, and generic/476 cause ext4
to emit error messages indicating that inline directory entries are
corrupted.  This occurs because the inline offset used to locate
inline directory entries in the inode body is not updated when an
xattr in that shared region is deleted and the region is shifted in
memory to recover the space it occupied.  If the deleted xattr precedes
the system.data attribute, which points to the inline directory entries,
that attribute will be moved further up in the region.  The inline
offset continues to point to whatever is located in system.data's former
location, with unfortunate effects when used to access directory entries
or (presumably) inline data in the inode body.

Signed-off-by: Eric Whitney <enwlinux@gmail.com>
---
 fs/ext4/xattr.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index dfc2e223bd10..e1c7b65d8d52 100644
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -1799,6 +1799,20 @@ static int ext4_xattr_set_entry(struct ext4_xattr_info *i,
 		memmove(here, (void *)here + size,
 			(void *)last - (void *)here + sizeof(__u32));
 		memset(last, 0, size);
+
+		/*
+		 * Update i_inline_off - moved ibody region might contain
+		 * system.data attribute.  Handling a failure here won't
+		 * cause other complications for setting an xattr.
+		 */
+		if (!is_block && ext4_has_inline_data(inode)) {
+			ret = ext4_find_inline_data_nolock(inode);
+			if (ret) {
+				ext4_warning_inode(inode,
+					"unable to update i_inline_off");
+				goto out;
+			}
+		}
 	} else if (s->not_found) {
 		/* Insert new name. */
 		size_t size = EXT4_XATTR_LEN(name_len);
-- 
2.30.2

Re: [PATCH] ext4: correct inline offset when handling xattrs in inode body

[Theodore Ts'o]

On Mon, 22 May 2023 14:15:20 -0400, Eric Whitney wrote:
> When run on a file system where the inline_data feature has been
> enabled, xfstests generic/269, generic/270, and generic/476 cause ext4
> to emit error messages indicating that inline directory entries are
> corrupted.  This occurs because the inline offset used to locate
> inline directory entries in the inode body is not updated when an
> xattr in that shared region is deleted and the region is shifted in
> memory to recover the space it occupied.  If the deleted xattr precedes
> the system.data attribute, which points to the inline directory entries,
> that attribute will be moved further up in the region.  The inline
> offset continues to point to whatever is located in system.data's former
> location, with unfortunate effects when used to access directory entries
> or (presumably) inline data in the inode body.
> 
> [...]

Applied, thanks!

[1/1] ext4: correct inline offset when handling xattrs in inode body
      commit: 48ef88508c16866ec9641fdda38642aa1f776fd4

Best regards,
-- 
Theodore Ts'o <tytso@mit.edu>