FAILED: Patch "smb: server: let send_done handle a completion without IB_SEND_SIGNALED" failed to apply to 5.10-stable tree

[Sasha Levin <sashal@kernel.org>]

The patch below does not apply to the 5.10-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>.

Thanks,
Sasha

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

From 9da82dc73cb03e85d716a2609364572367a5ff47 Mon Sep 17 00:00:00 2001
From: Stefan Metzmacher <metze@samba.org>
Date: Thu, 22 Jan 2026 18:16:47 +0100
Subject: [PATCH] smb: server: let send_done handle a completion without
 IB_SEND_SIGNALED

With smbdirect_send_batch processing we likely have requests without
IB_SEND_SIGNALED, which will be destroyed in the final request
that has IB_SEND_SIGNALED set.

If the connection is broken all requests are signaled
even without explicit IB_SEND_SIGNALED.

Cc: <stable@vger.kernel.org> # 6.18.x
Cc: Namjae Jeon <linkinjeon@kernel.org>
Cc: Steve French <smfrench@gmail.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: linux-cifs@vger.kernel.org
Cc: samba-technical@lists.samba.org
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
---
 fs/smb/server/transport_rdma.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/fs/smb/server/transport_rdma.c b/fs/smb/server/transport_rdma.c
index 5c0cc5064e8c0..c94068b78a1d2 100644
--- a/fs/smb/server/transport_rdma.c
+++ b/fs/smb/server/transport_rdma.c
@@ -1059,6 +1059,31 @@ static void send_done(struct ib_cq *cq, struct ib_wc *wc)
 		    ib_wc_status_msg(wc->status), wc->status,
 		    wc->opcode);
 
+	if (unlikely(!(sendmsg->wr.send_flags & IB_SEND_SIGNALED))) {
+		/*
+		 * This happens when smbdirect_send_io is a sibling
+		 * before the final message, it is signaled on
+		 * error anyway, so we need to skip
+		 * smbdirect_connection_free_send_io here,
+		 * otherwise is will destroy the memory
+		 * of the siblings too, which will cause
+		 * use after free problems for the others
+		 * triggered from ib_drain_qp().
+		 */
+		if (wc->status != IB_WC_SUCCESS)
+			goto skip_free;
+
+		/*
+		 * This should not happen!
+		 * But we better just close the
+		 * connection...
+		 */
+		pr_err("unexpected send completion wc->status=%s (%d) wc->opcode=%d\n",
+		       ib_wc_status_msg(wc->status), wc->status, wc->opcode);
+		smb_direct_disconnect_rdma_connection(sc);
+		return;
+	}
+
 	/*
 	 * Free possible siblings and then the main send_io
 	 */
@@ -1072,6 +1097,7 @@ static void send_done(struct ib_cq *cq, struct ib_wc *wc)
 	lcredits += 1;
 
 	if (wc->status != IB_WC_SUCCESS || wc->opcode != IB_WC_SEND) {
+skip_free:
 		pr_err("Send error. status='%s (%d)', opcode=%d\n",
 		       ib_wc_status_msg(wc->status), wc->status,
 		       wc->opcode);
-- 
2.51.0