From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754842Ab1AFAb5 (ORCPT ); Wed, 5 Jan 2011 19:31:57 -0500 Received: from kroah.org ([198.145.64.141]:36145 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754828Ab1AFAbz (ORCPT ); Wed, 5 Jan 2011 19:31:55 -0500 X-Mailbox-Line: From gregkh@clark.site Wed Jan 5 16:23:10 2011 Message-Id: <20110106002310.372154284@clark.site> User-Agent: quilt/0.48-11.2 Date: Wed, 05 Jan 2011 16:24:05 -0800 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Jesper Juhl , Tigran Aivazian , Shaohua Li , Ingo Molnar Subject: [146/152] x86/microcode: Fix double vfree() and remove redundant pointer checks before vfree() In-Reply-To: <20110106002500.GA3172@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.36-stable review patch. If anyone has any objections, please let us know. ------------------ From: Jesper Juhl commit 5cdd2de0a76d0ac47f107c8a7b32d75d25768dc1 upstream. In arch/x86/kernel/microcode_intel.c::generic_load_microcode() we have this: while (leftover) { ... if (get_ucode_data(mc, ucode_ptr, mc_size) || microcode_sanity_check(mc) < 0) { vfree(mc); break; } ... } if (mc) vfree(mc); This will cause a double free of 'mc'. This patch fixes that by just removing the vfree() call in the loop since 'mc' will be freed nicely just after we break out of the loop. There's also a second change in the patch. I noticed a lot of checks for pointers being NULL before passing them to vfree(). That's completely redundant since vfree() deals gracefully with being passed a NULL pointer. Removing the redundant checks yields a nice size decrease for the object file. Size before the patch: text data bss dec hex filename 4578 240 1032 5850 16da arch/x86/kernel/microcode_intel.o Size after the patch: text data bss dec hex filename 4489 240 984 5713 1651 arch/x86/kernel/microcode_intel.o Signed-off-by: Jesper Juhl Acked-by: Tigran Aivazian Cc: Shaohua Li LKML-Reference: Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/microcode_intel.c | 16 +++++----------- 1 file changed, 5 insertions(+), 11 deletions(-) --- a/arch/x86/kernel/microcode_intel.c +++ b/arch/x86/kernel/microcode_intel.c @@ -364,8 +364,7 @@ static enum ucode_state generic_load_mic /* For performance reasons, reuse mc area when possible */ if (!mc || mc_size > curr_mc_size) { - if (mc) - vfree(mc); + vfree(mc); mc = vmalloc(mc_size); if (!mc) break; @@ -374,13 +373,11 @@ static enum ucode_state generic_load_mic if (get_ucode_data(mc, ucode_ptr, mc_size) || microcode_sanity_check(mc) < 0) { - vfree(mc); break; } if (get_matching_microcode(&uci->cpu_sig, mc, new_rev)) { - if (new_mc) - vfree(new_mc); + vfree(new_mc); new_rev = mc_header.rev; new_mc = mc; mc = NULL; /* trigger new vmalloc */ @@ -390,12 +387,10 @@ static enum ucode_state generic_load_mic leftover -= mc_size; } - if (mc) - vfree(mc); + vfree(mc); if (leftover) { - if (new_mc) - vfree(new_mc); + vfree(new_mc); state = UCODE_ERROR; goto out; } @@ -405,8 +400,7 @@ static enum ucode_state generic_load_mic goto out; } - if (uci->mc) - vfree(uci->mc); + vfree(uci->mc); uci->mc = (struct microcode_intel *)new_mc; pr_debug("CPU%d found a matching microcode update with version 0x%x (current=0x%x)\n",