From: David Howells <dhowells@redhat.com>
Date: Mon, 25 Mar 2019 16:38:22 +0000 (+0000)
Subject: vfs: Fix refcounting of filenames in fs_parser
X-Git-Tag: v5.2.17~1
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=12434939ba58717e0259ffe7375f9aa7a5f1c0b8;p=users%2Fdwmw2%2Flinux.git

vfs: Fix refcounting of filenames in fs_parser

commit 7cdfa44227b0d8842d46a775cebe4311150cb8f2 upstream.

Fix an overput in which filename_lookup() unconditionally drops a ref to
the filename it was given, but this isn't taken account of in the caller,
fs_lookup_param().

Addresses-Coverity-ID: 1443811 ("Use after free")
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/fs/fs_parser.c b/fs/fs_parser.c
index 0d388faa25d16..460ea4206fa25 100644
--- a/fs/fs_parser.c
+++ b/fs/fs_parser.c
@@ -264,6 +264,7 @@ int fs_lookup_param(struct fs_context *fc,
 		return invalf(fc, "%s: not usable as path", param->key);
 	}
 
+	f->refcnt++; /* filename_lookup() drops our ref. */
 	ret = filename_lookup(param->dirfd, f, flags, _path, NULL);
 	if (ret < 0) {
 		errorf(fc, "%s: Lookup failure for '%s'", param->key, f->name);