smb: client: fix potential UAF and double free in smb2_open_file()

[ Upstream commit ebbbc4b ]

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

Fixes: e3a4363 ("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>

Author: pcacjr

fs/smb/client/smb2file.c

@@ -123,6 +123,8 @@ 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);