ubifs: Fix memory leak in lprobs self-check

BugLink: https://bugs.launchpad.net/bugs/1792419

commit eef19816 upstream.

Allocate the buffer after we return early.
Otherwise memory is being leaked.

Cc: <stable@vger.kernel.org>
Fixes: 1e51764a ("UBIFS: add new flash file system")
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

fs/ubifs/lprops.c

@@ -1091,10 +1091,6 @@ static int scan_check_cb(struct ubifs_info *c,
 		}
 	}
 
-	buf = __vmalloc(c->leb_size, GFP_NOFS, PAGE_KERNEL);
-	if (!buf)
-		return -ENOMEM;
-
 	/*
 	 * After an unclean unmount, empty and freeable LEBs
 	 * may contain garbage - do not scan them.
@@ -1113,6 +1109,10 @@ static int scan_check_cb(struct ubifs_info *c,
 		return LPT_SCAN_CONTINUE;
 	}
 
+	buf = __vmalloc(c->leb_size, GFP_NOFS, PAGE_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
 	sleb = ubifs_scan(c, lnum, 0, buf, 0);
 	if (IS_ERR(sleb)) {
 		ret = PTR_ERR(sleb);