From: Shyam Prasad N <sprasad@microsoft.com>
Date: Thu, 22 Jun 2023 18:16:03 +0000 (+0000)
Subject: cifs: prevent use-after-free by freeing the cfile later
X-Git-Tag: v6.1.39~234
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=4fe07d55a5461e66a55fbefb57f85ff0facea32b;p=platform%2Fkernel%2Flinux-starfive.git

cifs: prevent use-after-free by freeing the cfile later

[ Upstream commit 33f736187d08f6bc822117629f263b97d3df4165 ]

In smb2_compound_op we have a possible use-after-free
which can cause hard to debug problems later on.

This was revealed during stress testing with KASAN enabled
kernel. Fixing it by moving the cfile free call to
a few lines below, after the usage.

Fixes: 76894f3e2f71 ("cifs: improve symlink handling for smb2+")
Reviewed-by: Paulo Alcantara (SUSE) <pc@manguebit.com>
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/fs/smb/client/smb2inode.c b/fs/smb/client/smb2inode.c
index c97e049e29dd..57526bdbab17 100644
--- a/fs/smb/client/smb2inode.c
+++ b/fs/smb/client/smb2inode.c
@@ -397,9 +397,6 @@ static int smb2_compound_op(const unsigned int xid, struct cifs_tcon *tcon,
 					rsp_iov);
 
  finished:
-	if (cfile)
-		cifsFileInfo_put(cfile);
-
 	SMB2_open_free(&rqst[0]);
 	if (rc == -EREMCHG) {
 		pr_warn_once("server share %s deleted\n", tcon->tree_name);
@@ -513,6 +510,9 @@ static int smb2_compound_op(const unsigned int xid, struct cifs_tcon *tcon,
 		break;
 	}
 
+	if (cfile)
+		cifsFileInfo_put(cfile);
+
 	if (rc && err_iov && err_buftype) {
 		memcpy(err_iov, rsp_iov, 3 * sizeof(*err_iov));
 		memcpy(err_buftype, resp_buftype, 3 * sizeof(*err_buftype));