From: Trond Myklebust <trond.myklebust@hammerspace.com>
Date: Mon, 3 Jan 2022 14:50:16 -0500
Subject: [PATCH] NFSv4.1: Fix uninitialised variable in devicenotify
Git-commit: b05bf5c63b326ce1da84ef42498d8e0e292e694c
Patch-mainline: v5.17
References: git-fixes

When decode_devicenotify_args() exits with no entries, we need to
ensure that the struct cb_devicenotifyargs is initialised to
{ 0, NULL } in order to avoid problems in
nfs4_callback_devicenotify().

Reported-by: <rtm@csail.mit.edu>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Acked-by: NeilBrown <neilb@suse.com>

---
 fs/nfs/callback.h      |    2 +-
 fs/nfs/callback_proc.c |    2 +-
 fs/nfs/callback_xdr.c  |   18 +++++++++---------
 3 files changed, 11 insertions(+), 11 deletions(-)

--- a/fs/nfs/callback.h
+++ b/fs/nfs/callback.h
@@ -170,7 +170,7 @@ struct cb_devicenotifyitem {
 };
 
 struct cb_devicenotifyargs {
-	int				 ndevs;
+	uint32_t			 ndevs;
 	struct cb_devicenotifyitem	 *devs;
 };
 
--- a/fs/nfs/callback_proc.c
+++ b/fs/nfs/callback_proc.c
@@ -358,7 +358,7 @@ __be32 nfs4_callback_devicenotify(void *
 				  struct cb_process_state *cps)
 {
 	struct cb_devicenotifyargs *args = argp;
-	int i;
+	uint32_t i;
 	__be32 res = 0;
 	struct nfs_client *clp = cps->clp;
 	struct nfs_server *server = NULL;
--- a/fs/nfs/callback_xdr.c
+++ b/fs/nfs/callback_xdr.c
@@ -259,11 +259,9 @@ __be32 decode_devicenotify_args(struct s
 				void *argp)
 {
 	struct cb_devicenotifyargs *args = argp;
+	uint32_t tmp, n, i;
 	__be32 *p;
 	__be32 status = 0;
-	u32 tmp;
-	int n, i;
-	args->ndevs = 0;
 
 	/* Num of device notifications */
 	p = xdr_inline_decode(xdr, sizeof(uint32_t));
@@ -272,7 +270,7 @@ __be32 decode_devicenotify_args(struct s
 		goto out;
 	}
 	n = ntohl(*p++);
-	if (n <= 0)
+	if (n == 0)
 		goto out;
 	if (n > ULONG_MAX / sizeof(*args->devs)) {
 		status = htonl(NFS4ERR_BADXDR);
@@ -331,19 +329,21 @@ __be32 decode_devicenotify_args(struct s
 			dev->cbd_immediate = 0;
 		}
 
-		args->ndevs++;
-
 		dprintk("%s: type %d layout 0x%x immediate %d\n",
 			__func__, dev->cbd_notify_type, dev->cbd_layout_type,
 			dev->cbd_immediate);
 	}
+	args->ndevs = n;
+	dprintk("%s: ndevs %d\n", __func__, args->ndevs);
+	return 0;
+err:
+	kfree(args->devs);
 out:
+	args->devs = NULL;
+	args->ndevs = 0;
 	dprintk("%s: status %d ndevs %d\n",
 		__func__, ntohl(status), args->ndevs);
 	return status;
-err:
-	kfree(args->devs);
-	goto out;
 }
 
 static __be32 decode_sessionid(struct xdr_stream *xdr,