Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757645Ab2HPPpJ (ORCPT ); Thu, 16 Aug 2012 11:45:09 -0400 Received: from e9.ny.us.ibm.com ([32.97.182.139]:55752 "EHLO e9.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751920Ab2HPPpG (ORCPT ); Thu, 16 Aug 2012 11:45:06 -0400 Date: Thu, 16 Aug 2012 10:45:07 -0500 From: Kent Yoder To: Jesper Juhl Cc: linux-kernel@vger.kernel.org, tpmdd-devel@lists.sourceforge.net, Sirrix AG , Marcel Selhorst , Rajiv Andrade , Seiji Munetoh , Stefan Berger , Reiner Sailer , Kylene Hall Subject: Re: [PATCH] tpm: Do not dereference NULL pointer if acpi_os_map_memory() fails. Message-ID: <20120816154507.GA3850@linux.vnet.ibm.com> References: <20120808180750.GA24016@linux.vnet.ibm.com> <20120815201527.GC27618@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12081615-7182-0000-0000-0000024E8DA7 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1931 Lines: 57 On Thu, Aug 16, 2012 at 12:16:33AM +0200, Jesper Juhl wrote: > In drivers/char/tpm/tpm_acpi.c::read_log() we call > acpi_os_map_memory(). That call may fail for a number of reasons > (invalid address, out of memory etc). If the call fails it returns > NULL and we just pass that to memcpy() unconditionally, which will go > bad when it tries to dereference the pointer. > > Unfortunately we just get NULL back, so we can't really tell the user > exactely what went wrong, but we can at least avoid crashing and > return an error (-EIO seemed more generic and more suitable here than > -ENOMEM or something else, so I picked that). Thanks Jesper, applied here: git://github.com/shpedoikal/linux.git v3.6-rc1-tpmdd-staging Kent > > Signed-off-by: Jesper Juhl > --- > drivers/char/tpm/tpm_acpi.c | 5 +++++ > 1 file changed, 5 insertions(+) > > note: this patch is against git://github.com/shpedoikal/linux.git v3.6-rc1-tpmdd-staging > > diff --git a/drivers/char/tpm/tpm_acpi.c b/drivers/char/tpm/tpm_acpi.c > index a1bb5a18..fe3fa94 100644 > --- a/drivers/char/tpm/tpm_acpi.c > +++ b/drivers/char/tpm/tpm_acpi.c > @@ -96,6 +96,11 @@ int read_log(struct tpm_bios_log *log) > log->bios_event_log_end = log->bios_event_log + len; > > virt = acpi_os_map_memory(start, len); > + if (!virt) { > + kfree(log->bios_event_log); > + printk("%s: ERROR - Unable to map memory\n", __func__); > + return -EIO; > + } > > memcpy(log->bios_event_log, virt, len); > > -- > 1.7.11.4 > > > -- > Jesper Juhl http://www.chaosbits.net/ > Don't top-post http://www.catb.org/jargon/html/T/top-post.html > Plain text mails only, please. > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/