From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 02357C4320E for ; Mon, 16 Aug 2021 13:14:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E497B632A7 for ; Mon, 16 Aug 2021 13:14:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240084AbhHPNOv (ORCPT ); Mon, 16 Aug 2021 09:14:51 -0400 Received: from mail.kernel.org ([198.145.29.99]:56462 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239196AbhHPNJj (ORCPT ); Mon, 16 Aug 2021 09:09:39 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id C15CA610A0; Mon, 16 Aug 2021 13:09:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1629119344; bh=VFON9shimxrFJ1AC6LrHN9ae06WTIKEndI5RHPtWl3k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=zdUusNIcSsM+roMlOsYR8R9bDiuj1VQgjzu4mNG9PXPlzq7hcuL7nqqpilQ/Rtebw m2VHg/ASFvbMsR08PVRInyIldqzP3cfla24lS2yq/BqBo73RP9CSyY0NDSp9/fV855 YxYW6+UcGYr7YR3VisI0xqobbhse7C+wUPVc30FM= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Ard Biesheuvel , Benjamin Herrenschmidt , Sasha Levin Subject: [PATCH 5.10 69/96] efi/libstub: arm64: Force Image reallocation if BSS was not reserved Date: Mon, 16 Aug 2021 15:02:19 +0200 Message-Id: <20210816125437.267104668@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210816125434.948010115@linuxfoundation.org> References: <20210816125434.948010115@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Ard Biesheuvel [ Upstream commit 5b94046efb4706b3429c9c8e7377bd8d1621d588 ] Distro versions of GRUB replace the usual LoadImage/StartImage calls used to load the kernel image with some local code that fails to honor the allocation requirements described in the PE/COFF header, as it does not account for the image's BSS section at all: it fails to allocate space for it, and fails to zero initialize it. Since the EFI stub itself is allocated in the .init segment, which is in the middle of the image, its BSS section is not impacted by this, and the main consequence of this omission is that the BSS section may overlap with memory regions that are already used by the firmware. So let's warn about this condition, and force image reallocation to occur in this case, which works around the problem. Fixes: 82046702e288 ("efi/libstub/arm64: Replace 'preferred' offset with alignment check") Signed-off-by: Ard Biesheuvel Tested-by: Benjamin Herrenschmidt Signed-off-by: Sasha Levin --- drivers/firmware/efi/libstub/arm64-stub.c | 49 ++++++++++++++++++++++- 1 file changed, 48 insertions(+), 1 deletion(-) diff --git a/drivers/firmware/efi/libstub/arm64-stub.c b/drivers/firmware/efi/libstub/arm64-stub.c index 22ece1ad68a8..3dc54b9db054 100644 --- a/drivers/firmware/efi/libstub/arm64-stub.c +++ b/drivers/firmware/efi/libstub/arm64-stub.c @@ -34,6 +34,51 @@ efi_status_t check_platform_features(void) return EFI_SUCCESS; } +/* + * Distro versions of GRUB may ignore the BSS allocation entirely (i.e., fail + * to provide space, and fail to zero it). Check for this condition by double + * checking that the first and the last byte of the image are covered by the + * same EFI memory map entry. + */ +static bool check_image_region(u64 base, u64 size) +{ + unsigned long map_size, desc_size, buff_size; + efi_memory_desc_t *memory_map; + struct efi_boot_memmap map; + efi_status_t status; + bool ret = false; + int map_offset; + + map.map = &memory_map; + map.map_size = &map_size; + map.desc_size = &desc_size; + map.desc_ver = NULL; + map.key_ptr = NULL; + map.buff_size = &buff_size; + + status = efi_get_memory_map(&map); + if (status != EFI_SUCCESS) + return false; + + for (map_offset = 0; map_offset < map_size; map_offset += desc_size) { + efi_memory_desc_t *md = (void *)memory_map + map_offset; + u64 end = md->phys_addr + md->num_pages * EFI_PAGE_SIZE; + + /* + * Find the region that covers base, and return whether + * it covers base+size bytes. + */ + if (base >= md->phys_addr && base < end) { + ret = (base + size) <= end; + break; + } + } + + efi_bs_call(free_pool, memory_map); + + return ret; +} + /* * Although relocatable kernels can fix up the misalignment with respect to * MIN_KIMG_ALIGN, the resulting virtual text addresses are subtly out of @@ -92,7 +137,9 @@ efi_status_t handle_kernel_image(unsigned long *image_addr, } if (status != EFI_SUCCESS) { - if (IS_ALIGNED((u64)_text, min_kimg_align())) { + if (!check_image_region((u64)_text, kernel_memsize)) { + efi_err("FIRMWARE BUG: Image BSS overlaps adjacent EFI memory region\n"); + } else if (IS_ALIGNED((u64)_text, min_kimg_align())) { /* * Just execute from wherever we were loaded by the * UEFI PE/COFF loader if the alignment is suitable. -- 2.30.2