From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757920Ab3IEUdM (ORCPT ); Thu, 5 Sep 2013 16:33:12 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:52195 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757543Ab3IEU2p (ORCPT ); Thu, 5 Sep 2013 16:28:45 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Mark Young , Matt Craighead , Bruce Fields , Trond Myklebust Subject: [ 09/14] SUNRPC: Fix memory corruption issue on 32-bit highmem systems Date: Thu, 5 Sep 2013 13:28:20 -0700 Message-Id: <20130905202615.503113715@linuxfoundation.org> X-Mailer: git-send-email 1.8.4.3.gca3854a In-Reply-To: <20130905202614.354156084@linuxfoundation.org> References: <20130905202614.354156084@linuxfoundation.org> User-Agent: quilt/0.60-5.1.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Trond Myklebust commit 347e2233b7667e336d9f671f1a52dfa3f0416e2c upstream. Some architectures, such as ARM-32 do not return the same base address when you call kmap_atomic() twice on the same page. This causes problems for the memmove() call in the XDR helper routine "_shift_data_right_pages()", since it defeats the detection of overlapping memory ranges, and has been seen to corrupt memory. The fix is to distinguish between the case where we're doing an inter-page copy or not. In the former case of we know that the memory ranges cannot possibly overlap, so we can additionally micro-optimise by replacing memmove() with memcpy(). Reported-by: Mark Young Reported-by: Matt Craighead Cc: Bruce Fields Signed-off-by: Trond Myklebust Tested-by: Matt Craighead Signed-off-by: Greg Kroah-Hartman --- net/sunrpc/xdr.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) --- a/net/sunrpc/xdr.c +++ b/net/sunrpc/xdr.c @@ -233,10 +233,13 @@ _shift_data_right_pages(struct page **pa pgfrom_base -= copy; vto = kmap_atomic(*pgto); - vfrom = kmap_atomic(*pgfrom); - memmove(vto + pgto_base, vfrom + pgfrom_base, copy); + if (*pgto != *pgfrom) { + vfrom = kmap_atomic(*pgfrom); + memcpy(vto + pgto_base, vfrom + pgfrom_base, copy); + kunmap_atomic(vfrom); + } else + memmove(vto + pgto_base, vto + pgfrom_base, copy); flush_dcache_page(*pgto); - kunmap_atomic(vfrom); kunmap_atomic(vto); } while ((len -= copy) != 0);