FAILED: patch "[PATCH] smb/client: avoid possible NULL dereference in" failed to apply to 6.10-stable tree

FAILED: patch "[PATCH] smb/client: avoid possible NULL dereference in" failed to apply to 6.10-stable tree

[gregkh]

The patch below does not apply to the 6.10-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>.

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-6.10.y
git checkout FETCH_HEAD
git cherry-pick -x 74c2ab6d653b4c2354df65a7f7f2df1925a40a51
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2024081927-sustained-humbly-8aaf@gregkh' --subject-prefix 'PATCH 6.10.y' HEAD^..

Possible dependencies:

74c2ab6d653b ("smb/client: avoid possible NULL dereference in cifs_free_subrequest()")
519be989717c ("cifs: Add a tracepoint to track credits involved in R/W requests")

thanks,

greg k-h

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

From 74c2ab6d653b4c2354df65a7f7f2df1925a40a51 Mon Sep 17 00:00:00 2001
From: Su Hui <suhui@nfschina.com>
Date: Thu, 8 Aug 2024 20:23:32 +0800
Subject: [PATCH] smb/client: avoid possible NULL dereference in
 cifs_free_subrequest()

Clang static checker (scan-build) warning:
	cifsglob.h:line 890, column 3
	Access to field 'ops' results in a dereference of a null pointer.

Commit 519be989717c ("cifs: Add a tracepoint to track credits involved in
R/W requests") adds a check for 'rdata->server', and let clang throw this
warning about NULL dereference.

When 'rdata->credits.value != 0 && rdata->server == NULL' happens,
add_credits_and_wake_if() will call rdata->server->ops->add_credits().
This will cause NULL dereference problem. Add a check for 'rdata->server'
to avoid NULL dereference.

Cc: stable@vger.kernel.org
Fixes: 69c3c023af25 ("cifs: Implement netfslib hooks")
Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Su Hui <suhui@nfschina.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/smb/client/file.c b/fs/smb/client/file.c
index b2405dd4d4d4..45459af5044d 100644
--- a/fs/smb/client/file.c
+++ b/fs/smb/client/file.c
@@ -315,7 +315,7 @@ static void cifs_free_subrequest(struct netfs_io_subrequest *subreq)
 #endif
 	}
 
-	if (rdata->credits.value != 0)
+	if (rdata->credits.value != 0) {
 		trace_smb3_rw_credits(rdata->rreq->debug_id,
 				      rdata->subreq.debug_index,
 				      rdata->credits.value,
@@ -323,8 +323,12 @@ static void cifs_free_subrequest(struct netfs_io_subrequest *subreq)
 				      rdata->server ? rdata->server->in_flight : 0,
 				      -rdata->credits.value,
 				      cifs_trace_rw_credits_free_subreq);
+		if (rdata->server)
+			add_credits_and_wake_if(rdata->server, &rdata->credits, 0);
+		else
+			rdata->credits.value = 0;
+	}
 
-	add_credits_and_wake_if(rdata->server, &rdata->credits, 0);
 	if (rdata->have_xid)
 		free_xid(rdata->xid);
 }