From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.99]:44598 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730165AbeJIB4r (ORCPT ); Mon, 8 Oct 2018 21:56:47 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Stephen Rothwell , Steve French , Sasha Levin Subject: [PATCH 4.14 62/94] fs/cifs: suppress a string overflow warning Date: Mon, 8 Oct 2018 20:31:43 +0200 Message-Id: <20181008175609.361522977@linuxfoundation.org> In-Reply-To: <20181008175605.067676667@linuxfoundation.org> References: <20181008175605.067676667@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Stephen Rothwell [ Upstream commit bcfb84a996f6fa90b5e6e2954b2accb7a4711097 ] A powerpc build of cifs with gcc v8.2.0 produces this warning: fs/cifs/cifssmb.c: In function ‘CIFSSMBNegotiate’: fs/cifs/cifssmb.c:605:3: warning: ‘strncpy’ writing 16 bytes into a region of size 1 overflows the destination [-Wstringop-overflow=] strncpy(pSMB->DialectsArray+count, protocols[i].name, 16); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Since we are already doing a strlen() on the source, change the strncpy to a memcpy(). Signed-off-by: Stephen Rothwell Signed-off-by: Steve French Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- fs/cifs/cifssmb.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) --- a/fs/cifs/cifssmb.c +++ b/fs/cifs/cifssmb.c @@ -589,10 +589,15 @@ CIFSSMBNegotiate(const unsigned int xid, } count = 0; + /* + * We know that all the name entries in the protocols array + * are short (< 16 bytes anyway) and are NUL terminated. + */ for (i = 0; i < CIFS_NUM_PROT; i++) { - strncpy(pSMB->DialectsArray+count, protocols[i].name, 16); - count += strlen(protocols[i].name) + 1; - /* null at end of source and target buffers anyway */ + size_t len = strlen(protocols[i].name) + 1; + + memcpy(pSMB->DialectsArray+count, protocols[i].name, len); + count += len; } inc_rfc1001_len(pSMB, count); pSMB->ByteCount = cpu_to_le16(count);