FAILED: patch "[PATCH] ksmbd: fix extended session security negotiation for raw" failed to apply to 5.15-stable tree

The patch below does not apply to the 5.15-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-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x 6868f857514bbfd2ed10b9b566664dc4a8ca039d
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026110305-blimp-nape-e4b2@gregkh' --subject-prefix 'PATCH 5.15.y' 'HEAD^..'

Possible dependencies:

thanks,

greg k-h

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

From 6868f857514bbfd2ed10b9b566664dc4a8ca039d Mon Sep 17 00:00:00 2001
From: Namjae Jeon <[email protected]>
Date: Sun, 4 Oct 2026 09:42:27 +0900
Subject: [PATCH] ksmbd: fix extended session security negotiation for raw
NTLMSSP

ksmbd_build_ntlmssp_challenge_blob() only advertises extended session security when conn->use_spnego is true. As a result, raw NTLMSSP negotiation drops NTLMSSP_NEGOTIATE_EXTENDED_SEC from the challenge even when the client requested it.

A Windows capture shows an initial SPNEGO authentication succeeding, followed by a raw NTLMSSP negotiation on the same TCP connection. The raw challenge omits extended session security, and the client does not send an AUTHENTICATE message. The unfinished session then occupies the pending session slot, causing subsequent SESSION_SETUP requests to fail with STATUS_INSUFFICIENT_RESOURCES.

Set NTLMSSP_NEGOTIATE_EXTENDED_SEC whenever the client requests it, independently of the SPNEGO wrapper, as required by [MS-NLMP].

index 1b24eb3f3998..88953315b160 100644
@@ -336,8 +336,7 @@ ksmbd_build_ntlmssp_challenge_blob(struct challenge_message *chgblob,
 	if (cflags & NTLMSSP_REQUEST_TARGET)
 		flags |= NTLMSSP_REQUEST_TARGET;
 
-	if (conn->use_spnego &&
-	    (cflags & NTLMSSP_NEGOTIATE_EXTENDED_SEC))
+	if (cflags & NTLMSSP_NEGOTIATE_EXTENDED_SEC)
 		flags |= NTLMSSP_NEGOTIATE_EXTENDED_SEC;
 
 	if (cflags & NTLMSSP_NEGOTIATE_KEY_XCH)

From: Namjae Jeon <[email protected]>

[ Upstream commit 6868f857514bbfd2ed10b9b566664dc4a8ca039d ]

ksmbd_build_ntlmssp_challenge_blob() only advertises extended session security when conn->use_spnego is true. As a result, raw NTLMSSP negotiation drops NTLMSSP_NEGOTIATE_EXTENDED_SEC from the challenge even when the client requested it.

A Windows capture shows an initial SPNEGO authentication succeeding, followed by a raw NTLMSSP negotiation on the same TCP connection. The raw challenge omits extended session security, and the client does not send an AUTHENTICATE message. The unfinished session then occupies the pending session slot, causing subsequent SESSION_SETUP requests to fail with STATUS_INSUFFICIENT_RESOURCES.

Set NTLMSSP_NEGOTIATE_EXTENDED_SEC whenever the client requests it, independently of the SPNEGO wrapper, as required by [MS-NLMP].

---
 fs/ksmbd/auth.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

index cc4233c414b66..0fff634a74e11 100644
@@ -442,8 +442,7 @@ ksmbd_build_ntlmssp_challenge_blob(struct challenge_message *chgblob,
 	if (cflags & NTLMSSP_REQUEST_TARGET)
 		flags |= NTLMSSP_REQUEST_TARGET;
 
-	if (conn->use_spnego &&
-	    (cflags & NTLMSSP_NEGOTIATE_EXTENDED_SEC))
+	if (cflags & NTLMSSP_NEGOTIATE_EXTENDED_SEC)
 		flags |= NTLMSSP_NEGOTIATE_EXTENDED_SEC;
 
 	if (cflags & NTLMSSP_NEGOTIATE_KEY_XCH)

2.53.0