FAILED: patch "[PATCH] ksmbd: look up stream size by exact xattr name" failed to apply to 6.6-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 6.6-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 <stable@vger.kernel.org>.

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-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x 10ea20d6584ecdaf2f7505855412a856a88d8934
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026110445-either-jimmy-6232@gregkh' --subject-prefix 'PATCH 6.6.y' 'HEAD^..'

Possible dependencies:



thanks,

greg k-h

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

From 10ea20d6584ecdaf2f7505855412a856a88d8934 Mon Sep 17 00:00:00 2001
From: Gael Blivet <gael.blivet@gmail.com>
Date: Mon, 14 Sep 2026 01:26:36 +0200
Subject: [PATCH] ksmbd: look up stream size by exact xattr name

get_file_stream_info() walks the xattr list from a single
ksmbd_vfs_listxattr() and sizes each stream it finds with
ksmbd_vfs_casexattr_len(), which matches with strncasecmp(). Linux
xattr names are case-sensitive, so two streams differing only in case
report each other's size.

The loop already holds the exact name, so query it directly with
ksmbd_vfs_xattr_len(), which is what casexattr_len() calls once its
search succeeds. Make it non-static and declare it in vfs.h, and drop
the comment above it, which describes a different bug and no longer
matches the code.

This also drops a full listing per stream: casexattr_len() runs its own
listxattr on every call, so enumerating a file with N xattrs cost N
listings instead of one.

Fixes: 689f1eb3719d ("ksmbd: report actual xattr value length in stream enumeration")
Signed-off-by: Gael Blivet <gael.blivet@gmail.com>
Assisted-by: Claude:claude-opus-5
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>

diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c
index f46a29ce118f..10bcd724343c 100644
--- a/fs/smb/server/smb2pdu.c
+++ b/fs/smb/server/smb2pdu.c
@@ -6948,17 +6948,8 @@ static int get_file_stream_info(struct ksmbd_work *work,
 		streamlen *= 2;
 		kfree(stream_buf);
 		file_info->StreamNameLength = cpu_to_le32(streamlen);
-		/*
-		 * stream_name_len is the byte length of the xattr's *name*,
-		 * not its value -- same class of bug ksmbd_stream_eof()
-		 * (smb2pdu.c) already fixes for EndOfFile/AllocationSize on
-		 * a stream handle; this enumeration path needs the same
-		 * real xattr value length, not the name length reused as a
-		 * size.
-		 */
-		slen = ksmbd_vfs_casexattr_len(file_mnt_idmap(fp->filp),
-						path->dentry, stream_name,
-						strlen(stream_name) + 1);
+		slen = ksmbd_vfs_xattr_len(file_mnt_idmap(fp->filp),
+					   path->dentry, stream_name);
 		ssize = slen < 0 ? 0 : (loff_t)slen;
 		file_info->StreamSize = cpu_to_le64(ssize);
 		file_info->StreamAllocationSize = cpu_to_le64(ssize);
diff --git a/fs/smb/server/vfs.c b/fs/smb/server/vfs.c
index 0b03e0eec0a8..2e2c554bc2c1 100644
--- a/fs/smb/server/vfs.c
+++ b/fs/smb/server/vfs.c
@@ -842,8 +842,8 @@ ssize_t ksmbd_vfs_listxattr(struct dentry *dentry, char **list)
 	return size;
 }
 
-static ssize_t ksmbd_vfs_xattr_len(const struct mnt_idmap *idmap,
-				   struct dentry *dentry, char *xattr_name)
+ssize_t ksmbd_vfs_xattr_len(const struct mnt_idmap *idmap,
+			    struct dentry *dentry, char *xattr_name)
 {
 	return vfs_getxattr(idmap, dentry, xattr_name, NULL, 0);
 }
diff --git a/fs/smb/server/vfs.h b/fs/smb/server/vfs.h
index 12f3ce79b3c5..216c76291fc1 100644
--- a/fs/smb/server/vfs.h
+++ b/fs/smb/server/vfs.h
@@ -108,6 +108,8 @@ ssize_t ksmbd_vfs_getxattr(const struct mnt_idmap *idmap,
 			   struct dentry *dentry,
 			   char *xattr_name,
 			   char **xattr_buf);
+ssize_t ksmbd_vfs_xattr_len(const struct mnt_idmap *idmap,
+			    struct dentry *dentry, char *xattr_name);
 ssize_t ksmbd_vfs_getcasexattr(const struct mnt_idmap *idmap,
 			       struct dentry *dentry, char *attr_name,
 			       int attr_name_len, char **attr_value);