From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753099AbbGNXrm (ORCPT ); Tue, 14 Jul 2015 19:47:42 -0400 Received: from mail-lb0-f169.google.com ([209.85.217.169]:33880 "EHLO mail-lb0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752294AbbGNXrk (ORCPT ); Tue, 14 Jul 2015 19:47:40 -0400 Date: Wed, 15 Jul 2015 01:47:35 +0200 From: Horacio Mijail Anton Quiles To: Andrew Morton , Andy Shevchenko , David Howells , Vivek Goyal , linux-kernel@vger.kernel.org, trivial@kernel.org, Joe Perches , Geert Uytterhoeven Subject: [PATCH v6] hexdump: fix for non-aligned buffers Message-ID: <20150714234735.GA31212@mija-VirtualBox> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org An hexdump with a buf not aligned to the groupsize causes non-naturally-aligned memory accesses. This was causing a kernel panic on the processor BlackFin BF527, when such an unaligned buffer was fed by the function ubifs_scanned_corruption in fs/ubifs/scan.c . To fix this, change accesses to the contents of the buffer so they go through get_unaligned(). This change should be harmless to unaligned- access-capable architectures, and any performance hit should be anyway dwarfed by the snprintf() processing time. Signed-off-by: Horacio Mijail Antón Quiles --- Changes in v6: - Removed unnecessary cast of u64 to unsigned long long, since currently they are equivalent (per Geer Uytterhoeven's indication) Changes in v5: - Instead of trying to detect non-unaligned-capable architectures, change all accesses to unconditionally use get_unaligned() (per Andrew Morton's and Geert Uytterhoeven's comments) Changes in v4: - Added space before "*/" (per Joe Perches' indication) Changes in v3: - Removed trailing whitespace (per Joe Perches' indication) - Changed mail headers to avoid encoding issues (per Joe Perches' hint) Changes in v2: - Changed from ad-hoc calculation to IS_ALIGNED() for readability (per Joe Perches' indication) - Made the explanation clearer (aligned vs naturally aligned) --- lib/hexdump.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/lib/hexdump.c b/lib/hexdump.c index 7ea0969..8d74c20 100644 --- a/lib/hexdump.c +++ b/lib/hexdump.c @@ -11,6 +11,7 @@ #include #include #include +#include const char hex_asc[] = "0123456789abcdef"; EXPORT_SYMBOL(hex_asc); @@ -139,7 +140,7 @@ int hex_dump_to_buffer(const void *buf, size_t len, int rowsize, int groupsize, for (j = 0; j < ngroups; j++) { ret = snprintf(linebuf + lx, linebuflen - lx, "%s%16.16llx", j ? " " : "", - (unsigned long long)*(ptr8 + j)); + get_unaligned(ptr8 + j)); if (ret >= linebuflen - lx) goto overflow1; lx += ret; @@ -150,7 +151,7 @@ int hex_dump_to_buffer(const void *buf, size_t len, int rowsize, int groupsize, for (j = 0; j < ngroups; j++) { ret = snprintf(linebuf + lx, linebuflen - lx, "%s%8.8x", j ? " " : "", - *(ptr4 + j)); + get_unaligned(ptr4 + j)); if (ret >= linebuflen - lx) goto overflow1; lx += ret; @@ -161,7 +162,7 @@ int hex_dump_to_buffer(const void *buf, size_t len, int rowsize, int groupsize, for (j = 0; j < ngroups; j++) { ret = snprintf(linebuf + lx, linebuflen - lx, "%s%4.4x", j ? " " : "", - *(ptr2 + j)); + get_unaligned(ptr2 + j)); if (ret >= linebuflen - lx) goto overflow1; lx += ret; -- 2.1.4