9p: Avoid creating multiple slab caches with the same name

In the spirit of [1], avoid creating multiple slab caches with the same
name. Instead, add the dev_name into the mix.

[1]: https://lore.kernel.org/all/20240807090746.2146479-1-pedro.falcato@gmail.com/Signed-off-by: Pedro Falcato <pedro.falcato@gmail.com>
Reported-by: syzbot+3c5d43e97993e1fa612b@syzkaller.appspotmail.com
Message-ID: <20240807094725.2193423-1-pedro.falcato@gmail.com>
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>

net/9p/client.c

@@ -979,6 +979,7 @@ struct p9_client *p9_client_create(const char *dev_name, char *options)
 	int err;
 	struct p9_client *clnt;
 	char *client_id;
+	char *cache_name;
 
 	clnt = kmalloc(sizeof(*clnt), GFP_KERNEL);
 	if (!clnt)
@@ -1035,15 +1036,22 @@ struct p9_client *p9_client_create(const char *dev_name, char *options)
 	if (err)
 		goto close_trans;
 
+	cache_name = kasprintf(GFP_KERNEL, "9p-fcall-cache-%s", dev_name);
+	if (!cache_name) {
+		err = -ENOMEM;
+		goto close_trans;
+	}
+
 	/* P9_HDRSZ + 4 is the smallest packet header we can have that is
 	 * followed by data accessed from userspace by read
 	 */
 	clnt->fcall_cache =
-		kmem_cache_create_usercopy("9p-fcall-cache", clnt->msize,
+		kmem_cache_create_usercopy(cache_name, clnt->msize,
 					   0, 0, P9_HDRSZ + 4,
 					   clnt->msize - (P9_HDRSZ + 4),
 					   NULL);
 
+	kfree(cache_name);
 	return clnt;
 
 close_trans: