FAILED: patch "[PATCH] ovl: skip copy up of empty security.capability" 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 50912a1715b8a7c614b654011a0db750e372b43e
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026110441-verbalize-sauna-b06f@gregkh' --subject-prefix 'PATCH 6.1.y' 'HEAD^..'

Possible dependencies:

thanks,

greg k-h

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

From 50912a1715b8a7c614b654011a0db750e372b43e Mon Sep 17 00:00:00 2001
From: Amir Goldstein <[email protected]>
Date: Sun, 18 Oct 2026 11:52:52 +0200
Subject: [PATCH] ovl: skip copy up of empty security.capability

ovl_copy_xattr() gives up if it can't read an attribute that listxattr() has named. An empty security.capability, which anybody has been able to store on any file for a long time, is such a case: it is listed, and getxattr() has nothing to return for it. A file in a lower layer that carries one can't be copied up: it can't be written to, renamed or have its mode changed.

There is nothing to copy if there are no data. Go on with the next one.

[amir: treat -EINVAL as no capability too, and do the same in
ovl_copy_up_meta_inode_data()]

index 286978d47ef7..0cd76ca5b8d7 100644
@@ -75,6 +75,15 @@ static int ovl_copy_acl(struct ovl_fs *ofs, const struct path *path,
 static ssize_t ovl_getxattr_value(const struct path *path, char *name,
 				  char **value, ssize_t *value_size);
 
+/*
+ * Any user can store an empty security.capability, which fails to read with
+ * -EINVAL.  It grants no capability, so treat it as none, like no xattr.
+ */
+static bool ovl_no_fscap(ssize_t err)
+{
+	return err == -ENODATA || err == -EOPNOTSUPP || err == -EINVAL;
+}
+
 int ovl_copy_xattr(struct super_block *sb, const struct path *oldpath, struct dentry *new)
 {
 	struct dentry *old = oldpath->dentry;

@@ -134,6 +143,10 @@ int ovl_copy_xattr(struct super_block *sb, const struct path *oldpath, struct de
 
 		size = ovl_getxattr_value(oldpath, name, &value, &value_size);
 		if (size < 0) {
+			if (!strcmp(name, XATTR_NAME_CAPS) && ovl_no_fscap(size)) {
+				error = 0;
+				continue;
+			}
 			error = size;
 			break;
 		}

@@ -1099,9 +1112,9 @@ static int ovl_copy_up_meta_inode_data(struct ovl_copy_up_ctx *c)
 	if (c->stat.size) {
 		err = cap_size = ovl_getxattr_value(&upperpath, XATTR_NAME_CAPS,
 						    &capability, &cap_size);
-		if (cap_size == -ENODATA || cap_size == -EOPNOTSUPP)
+		if (ovl_no_fscap(cap_size))
 			cap_size = 0;
-		if (cap_size < 0)
+		else if (cap_size < 0)
 			goto out;
 	}