FAILED: patch "[PATCH] ksmbd: smbdirect: verify remaining_data_length respects" failed to apply to 5.15-stable tree

[<gregkh@linuxfoundation.org>]

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 <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-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x e1868ba37fd27c6a68e31565402b154beaa65df0
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2025092135-estate-gander-564d@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

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

From e1868ba37fd27c6a68e31565402b154beaa65df0 Mon Sep 17 00:00:00 2001
From: Stefan Metzmacher <metze@samba.org>
Date: Thu, 11 Sep 2025 10:05:23 +0900
Subject: [PATCH] ksmbd: smbdirect: verify remaining_data_length respects
 max_fragmented_recv_size

This is inspired by the check for data_offset + data_length.

Cc: Steve French <smfrench@gmail.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: linux-cifs@vger.kernel.org
Cc: samba-technical@lists.samba.org
Cc: stable@vger.kernel.org
Fixes: 2ea086e35c3d ("ksmbd: add buffer validation for smb direct")
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/smb/server/transport_rdma.c b/fs/smb/server/transport_rdma.c
index d52f37578276..6550bd9f002c 100644
--- a/fs/smb/server/transport_rdma.c
+++ b/fs/smb/server/transport_rdma.c
@@ -554,7 +554,7 @@ static void recv_done(struct ib_cq *cq, struct ib_wc *wc)
 	case SMB_DIRECT_MSG_DATA_TRANSFER: {
 		struct smb_direct_data_transfer *data_transfer =
 			(struct smb_direct_data_transfer *)recvmsg->packet;
-		unsigned int data_offset, data_length;
+		u32 remaining_data_length, data_offset, data_length;
 		int avail_recvmsg_count, receive_credits;
 
 		if (wc->byte_len <
@@ -564,6 +564,7 @@ static void recv_done(struct ib_cq *cq, struct ib_wc *wc)
 			return;
 		}
 
+		remaining_data_length = le32_to_cpu(data_transfer->remaining_data_length);
 		data_length = le32_to_cpu(data_transfer->data_length);
 		data_offset = le32_to_cpu(data_transfer->data_offset);
 		if (wc->byte_len < data_offset ||
@@ -572,6 +573,14 @@ static void recv_done(struct ib_cq *cq, struct ib_wc *wc)
 			smb_direct_disconnect_rdma_connection(t);
 			return;
 		}
+		if (remaining_data_length > t->max_fragmented_recv_size ||
+		    data_length > t->max_fragmented_recv_size ||
+		    (u64)remaining_data_length + (u64)data_length >
+		    (u64)t->max_fragmented_recv_size) {
+			put_recvmsg(t, recvmsg);
+			smb_direct_disconnect_rdma_connection(t);
+			return;
+		}
 
 		if (data_length) {
 			if (t->full_packet_received)