From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sasha Levin Subject: Re: [PATCH AUTOSEL 4.19 17/49] efi/x86/Add missing error handling to old_memmap 1:1 mapping code Date: Wed, 19 Jun 2019 16:58:12 -0400 Message-ID: <20190619205812.GE2226@sasha-vm> References: <20190608114232.8731-1-sashal@kernel.org> <20190608114232.8731-17-sashal@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Ard Biesheuvel Cc: Linux Kernel Mailing List , stable , Gen Zhang , Linus Torvalds , Peter Zijlstra , Rob Bradford , Thomas Gleixner , linux-efi , Ingo Molnar , platform-driver-x86@vger.kernel.org List-Id: platform-driver-x86.vger.kernel.org On Sun, Jun 09, 2019 at 08:14:29PM +0200, Ard Biesheuvel wrote: >On Sat, 8 Jun 2019 at 13:43, Sasha Levin wrote: >> >> From: Gen Zhang >> >> [ Upstream commit 4e78921ba4dd0aca1cc89168f45039add4183f8e ] >> >> The old_memmap flow in efi_call_phys_prolog() performs numerous memory >> allocations, and either does not check for failure at all, or it does >> but fails to propagate it back to the caller, which may end up calling >> into the firmware with an incomplete 1:1 mapping. >> >> So let's fix this by returning NULL from efi_call_phys_prolog() on >> memory allocation failures only, and by handling this condition in the >> caller. Also, clean up any half baked sets of page tables that we may >> have created before returning with a NULL return value. >> >> Note that any failure at this level will trigger a panic() two levels >> up, so none of this makes a huge difference, but it is a nice cleanup >> nonetheless. >> >> [ardb: update commit log, add efi_call_phys_epilog() call on error path] >> >> Signed-off-by: Gen Zhang >> Signed-off-by: Ard Biesheuvel >> Cc: Linus Torvalds >> Cc: Peter Zijlstra >> Cc: Rob Bradford >> Cc: Thomas Gleixner >> Cc: linux-efi@vger.kernel.org >> Link: http://lkml.kernel.org/r/20190525112559.7917-2-ard.biesheuvel@linaro.org >> Signed-off-by: Ingo Molnar >> Signed-off-by: Sasha Levin > >This was already discussed in the thread that proposed this patch for >stable: please don't queue this right now, the patches are more likely >to harm than hurt, and they certainly don't fix a security >vulnerability, as has been claimed. I've dropped this, thank you. -- Thanks, Sasha