netdev - [PATCH 2/2] 9p: destroy client in symmetric order

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Message-Id: <743fc62b2e8d15c84e234744e3f3f136c467752d.1664442592.git.leonro@nvidia.com>
Date:   Thu, 29 Sep 2022 12:37:56 +0300
From:   Leon Romanovsky <leon@...nel.org>
To:     v9fs-developer@...ts.sourceforge.net
Cc:     linux_oss@...debyte.com, linux-kernel@...r.kernel.org,
        syzkaller-bugs@...glegroups.com,
        Dominique Martinet <asmadeus@...ewreck.org>,
        syzbot+67d13108d855f451cafc@...kaller.appspotmail.com,
        davem@...emloft.net, edumazet@...gle.com, ericvh@...il.com,
        kuba@...nel.org, lucho@...kov.net, netdev@...r.kernel.org,
        syzbot+de52531662ebb8823b26@...kaller.appspotmail.com
Subject: [PATCH 2/2] 9p: destroy client in symmetric order

Make sure that all variables are initialized and released in correct
order.

Reported-by: syzbot+de52531662ebb8823b26@...kaller.appspotmail.com
Signed-off-by: Leon Romanovsky <leon@...nel.org>
---
 net/9p/client.c | 37 ++++++++++++-------------------------
 1 file changed, 12 insertions(+), 25 deletions(-)

diff --git a/net/9p/client.c b/net/9p/client.c
index aaa37b07e30a..8277e33506e7 100644
--- a/net/9p/client.c
+++ b/net/9p/client.c
@@ -179,7 +179,6 @@ static int parse_opts(char *opts, struct p9_client *clnt)
 				goto free_and_return;
 			}
 
-			v9fs_put_trans(clnt->trans_mod);
 			clnt->trans_mod = v9fs_get_trans_by_name(s);
 			if (!clnt->trans_mod) {
 				pr_info("Could not find request transport: %s\n",
@@ -187,7 +186,7 @@ static int parse_opts(char *opts, struct p9_client *clnt)
 				ret = -EINVAL;
 			}
 			kfree(s);
-			break;
+			goto free_and_return;
 		case Opt_legacy:
 			clnt->proto_version = p9_proto_legacy;
 			break;
@@ -211,9 +210,14 @@ static int parse_opts(char *opts, struct p9_client *clnt)
 		}
 	}
 
+	clnt->trans_mod = v9fs_get_default_trans();
+	if (!clnt->trans_mod) {
+		ret = -EPROTONOSUPPORT;
+		p9_debug(P9_DEBUG_ERROR,
+			 "No transport defined or default transport\n");
+	}
+
 free_and_return:
-	if (ret)
-		v9fs_put_trans(clnt->trans_mod);
 	kfree(tmp_options);
 	return ret;
 }
@@ -956,19 +960,14 @@ static int p9_client_version(struct p9_client *c)
 
 struct p9_client *p9_client_create(const char *dev_name, char *options)
 {
-	int err;
 	struct p9_client *clnt;
 	char *client_id;
+	int err = 0;
 
-	err = 0;
-	clnt = kmalloc(sizeof(*clnt), GFP_KERNEL);
+	clnt = kzalloc(sizeof(*clnt), GFP_KERNEL);
 	if (!clnt)
 		return ERR_PTR(-ENOMEM);
 
-	clnt->trans_mod = NULL;
-	clnt->trans = NULL;
-	clnt->fcall_cache = NULL;
-
 	client_id = utsname()->nodename;
 	memcpy(clnt->name, client_id, strlen(client_id) + 1);
 
@@ -980,16 +979,6 @@ struct p9_client *p9_client_create(const char *dev_name, char *options)
 	if (err < 0)
 		goto free_client;
 
-	if (!clnt->trans_mod)
-		clnt->trans_mod = v9fs_get_default_trans();
-
-	if (!clnt->trans_mod) {
-		err = -EPROTONOSUPPORT;
-		p9_debug(P9_DEBUG_ERROR,
-			 "No transport defined or default transport\n");
-		goto free_client;
-	}
-
 	p9_debug(P9_DEBUG_MUX, "clnt %p trans %p msize %d protocol %d\n",
 		 clnt, clnt->trans_mod, clnt->msize, clnt->proto_version);
 
@@ -1044,9 +1033,8 @@ void p9_client_destroy(struct p9_client *clnt)
 
 	p9_debug(P9_DEBUG_MUX, "clnt %p\n", clnt);
 
-	if (clnt->trans_mod)
-		clnt->trans_mod->close(clnt);
-
+	kmem_cache_destroy(clnt->fcall_cache);
+	clnt->trans_mod->close(clnt);
 	v9fs_put_trans(clnt->trans_mod);
 
 	idr_for_each_entry(&clnt->fids, fid, id) {
@@ -1056,7 +1044,6 @@ void p9_client_destroy(struct p9_client *clnt)
 
 	p9_tag_cleanup(clnt);
 
-	kmem_cache_destroy(clnt->fcall_cache);
 	kfree(clnt);
 }
 EXPORT_SYMBOL(p9_client_destroy);
-- 
2.37.3