linux-kernel - Re: [PATCH] Xen: EFI: Parse DT parameters for Xen specific UEFI

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20160511122948.GV2839@codeblueprint.co.uk>
Date:	Wed, 11 May 2016 13:29:48 +0100
From:	Matt Fleming <matt@...eblueprint.co.uk>
To:	Mathieu Poirier <mathieu.poirier@...aro.org>
Cc:	Shannon Zhao <zhaoshenglong@...wei.com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will.deacon@....com>, sstabellini@...nel.org,
	stefano@...reto.com, julien.grall@....com,
	ard.biesheuvel@...aro.org, xen-devel@...ts.xen.org,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	linux-efi@...r.kernel.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	shannon.zhao@...aro.org, peter.huangpeng@...wei.com
Subject: Re: [PATCH] Xen: EFI: Parse DT parameters for Xen specific UEFI

On Fri, 06 May, at 09:52:42AM, Mathieu Poirier wrote:
> > +static int __init efi_remap_init(void)
> > +{
> > +       u64 mapsize;
> > +
> > +       pr_info("Remapping and enabling EFI services.\n");
> > +
> > +       mapsize = memmap.map_end - memmap.map;
> > +       memmap.map = (__force void *)ioremap_cache(memmap.phys_map,
> > +                                                  mapsize);
> > +       if (!memmap.map) {
> > +               pr_err("Failed to remap EFI memory map\n");
> > +               return -ENOMEM;
> > +       }
> > +       memmap.map_end = memmap.map + mapsize;
> > +       efi.memmap = &memmap;
> > +
> > +       efi.systab = (__force void *)ioremap_cache(efi_system_table,
> > +                                                  sizeof(efi_system_table_t));
> > +       if (!efi.systab) {
> 
> Is there a reason why memmap.map isn't iounmap() in the error path?
> The original code didn't have it either, hence the question.

I suspect that is a bug.

In reality, if you can't access the EFI System Table because you fail
to map it I would guess you are going to crash very, very quickly
anyhow.