[PATCH 6.18 032/641] smb: client: fix potential UAF and double free in smb2_open_file()

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

6.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Paulo Alcantara <pc@manguebit.org>

[ Upstream commit ebbbc4bfad4cb355d17c671223d0814ee3ef4eda ]

Zero out @err_iov and @err_buftype before retrying SMB2_open() to
prevent an UAF bug if @data != NULL, otherwise a double free.

Fixes: e3a43633023e ("smb/client: fix memory leak in smb2_open_file()")
Reported-by: David Howells <dhowells@redhat.com>
Closes: https://lore.kernel.org/r/2892312.1770306653@warthog.procyon.org.uk
Signed-off-by: Paulo Alcantara (Red Hat) <pc@manguebit.org>
Reviewed-by: David Howells <dhowells@redhat.com>
Reviewed-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
Cc: linux-cifs@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/smb/client/smb2file.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/smb/client/smb2file.c b/fs/smb/client/smb2file.c
index 03f90553d8319..e6cdf2efc7f4f 100644
--- a/fs/smb/client/smb2file.c
+++ b/fs/smb/client/smb2file.c
@@ -178,6 +178,8 @@ int smb2_open_file(const unsigned int xid, struct cifs_open_parms *oparms, __u32
 		       &err_buftype);
 	if (rc == -EACCES && retry_without_read_attributes) {
 		free_rsp_buf(err_buftype, err_iov.iov_base);
+		memset(&err_iov, 0, sizeof(err_iov));
+		err_buftype = CIFS_NO_BUFFER;
 		oparms->desired_access &= ~FILE_READ_ATTRIBUTES;
 		rc = SMB2_open(xid, oparms, smb2_path, &smb2_oplock, smb2_data, NULL, &err_iov,
 			       &err_buftype);
-- 
2.51.0