FAILED: patch "[PATCH] xfs: do not propagate ENODATA disk errors into xattr code" failed to apply to 6.1-stable tree

The patch below does not apply to the 6.1-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y
git checkout FETCH_HEAD
git cherry-pick -x ae668cd567a6a7622bc813ee0bb61c42bed61ba7
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2025090111-poem-retold-4ac2@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From ae668cd567a6a7622bc813ee0bb61c42bed61ba7 Mon Sep 17 00:00:00 2001
From: Eric Sandeen <[email protected]>
Date: Fri, 22 Aug 2025 12:55:56 -0500
Subject: [PATCH] xfs: do not propagate ENODATA disk errors into xattr code

ENODATA (aka ENOATTR) has a very specific meaning in the xfs xattr code; namely, that the requested attribute name could not be found.

However, a medium error from disk may also return ENODATA. At best, this medium error may escape to userspace as "attribute not found" when in fact it's an IO (disk) error.

At worst, we may oops in xfs_attr_leaf_get() when we do:

	error = xfs_attr_leaf_hasname(args, &bp);
	if (error == -ENOATTR)  {
		xfs_trans_brelse(args->trans, bp);
		return error;
	}

because an ENODATA/ENOATTR error from disk leaves us with a null bp, and the xfs_trans_brelse will then null-deref it.

As discussed on the list, we really need to modify the lower level IO functions to trap all disk errors and ensure that we don't let unique errors like this leak up into higher xfs functions - many like this should be remapped to EIO.

However, this patch directly addresses a reported bug in the xattr code, and should be safe to backport to stable kernels. A larger-scope patch to handle more unique errors at lower levels can follow later.

(Note, prior to 07120f1abdff we did not oops, but we did return the wrong error code to userspace.)

index 4c44ce1c8a64..bff3dc226f81 100644
@@ -435,6 +435,13 @@ xfs_attr_rmtval_get(
 					0, &bp, &xfs_attr3_rmt_buf_ops);
 			if (xfs_metadata_is_sick(error))
 				xfs_dirattr_mark_sick(args->dp, XFS_ATTR_FORK);
+			/*
+			 * ENODATA from disk implies a disk medium failure;
+			 * ENODATA for xattrs means attribute not found, so
+			 * disambiguate that here.
+			 */
+			if (error == -ENODATA)
+				error = -EIO;
 			if (error)
 				return error;
 

index 17d9e6154f19..723a0643b838 100644
@@ -2833,6 +2833,12 @@ xfs_da_read_buf(
 			&bp, ops);
 	if (xfs_metadata_is_sick(error))
 		xfs_dirattr_mark_sick(dp, whichfork);
+	/*
+	 * ENODATA from disk implies a disk medium failure; ENODATA for
+	 * xattrs means attribute not found, so disambiguate that here.
+	 */
+	if (error == -ENODATA && whichfork == XFS_ATTR_FORK)
+		error = -EIO;
 	if (error)
 		goto out_free;
 

From: Eric Sandeen <[email protected]>

[ Upstream commit ae668cd567a6a7622bc813ee0bb61c42bed61ba7 ]

ENODATA (aka ENOATTR) has a very specific meaning in the xfs xattr code; namely, that the requested attribute name could not be found.

However, a medium error from disk may also return ENODATA. At best, this medium error may escape to userspace as "attribute not found" when in fact it's an IO (disk) error.

At worst, we may oops in xfs_attr_leaf_get() when we do:

	error = xfs_attr_leaf_hasname(args, &bp);
	if (error == -ENOATTR)  {
		xfs_trans_brelse(args->trans, bp);
		return error;
	}

because an ENODATA/ENOATTR error from disk leaves us with a null bp, and the xfs_trans_brelse will then null-deref it.

As discussed on the list, we really need to modify the lower level IO functions to trap all disk errors and ensure that we don't let unique errors like this leak up into higher xfs functions - many like this should be remapped to EIO.

However, this patch directly addresses a reported bug in the xattr code, and should be safe to backport to stable kernels. A larger-scope patch to handle more unique errors at lower levels can follow later.

(Note, prior to 07120f1abdff we did not oops, but we did return the wrong error code to userspace.)

---
 fs/xfs/libxfs/xfs_attr_remote.c | 7 +++++++
 fs/xfs/libxfs/xfs_da_btree.c    | 6 ++++++
 2 files changed, 13 insertions(+)

index 54de405cbab5a..4d369876487bd 100644
@@ -418,6 +418,13 @@ xfs_attr_rmtval_get(
 			dblkcnt = XFS_FSB_TO_BB(mp, map[i].br_blockcount);
 			error = xfs_buf_read(mp->m_ddev_targp, dblkno, dblkcnt,
 					0, &bp, &xfs_attr3_rmt_buf_ops);
+			/*
+			 * ENODATA from disk implies a disk medium failure;
+			 * ENODATA for xattrs means attribute not found, so
+			 * disambiguate that here.
+			 */
+			if (error == -ENODATA)
+				error = -EIO;
 			if (error)
 				return error;
 

index 12e3cca804b7e..3ec681fdc075b 100644
@@ -2648,6 +2648,12 @@ xfs_da_read_buf(
 
 	error = xfs_trans_read_buf_map(mp, tp, mp->m_ddev_targp, mapp, nmap, 0,
 			&bp, ops);
+	/*
+	 * ENODATA from disk implies a disk medium failure; ENODATA for
+	 * xattrs means attribute not found, so disambiguate that here.
+	 */
+	if (error == -ENODATA && whichfork == XFS_ATTR_FORK)
+		error = -EIO;
 	if (error)
 		goto out_free;
 

2.50.1