Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965303AbcLVKYE (ORCPT ); Thu, 22 Dec 2016 05:24:04 -0500 Received: from mail-wm0-f65.google.com ([74.125.82.65]:34865 "EHLO mail-wm0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758478AbcLVKYB (ORCPT ); Thu, 22 Dec 2016 05:24:01 -0500 From: Nicolai Stange To: Matt Fleming Cc: Ard Biesheuvel , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, =?UTF-8?q?Mika=20Penttil=C3=A4?= , Nicolai Stange Subject: [PATCH v2 1/2] x86/efi: don't allocate memmap through memblock after mm_init() Date: Thu, 22 Dec 2016 11:23:39 +0100 Message-Id: <20161222102340.2689-1-nicstange@gmail.com> X-Mailer: git-send-email 2.11.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4414 Lines: 128 With commit 4bc9f92e64c8 ("x86/efi-bgrt: Use efi_mem_reserve() to avoid copying image data"), efi_bgrt_init() calls into the memblock allocator through efi_mem_reserve() => efi_arch_mem_reserve() *after* mm_init() has been called. Indeed, KASAN reports a bad read access later on in efi_free_boot_services(): BUG: KASAN: use-after-free in efi_free_boot_services+0xae/0x24c at addr ffff88022de12740 Read of size 4 by task swapper/0/0 page:ffffea0008b78480 count:0 mapcount:-127 mapping: (null) index:0x1 flags: 0x5fff8000000000() [...] Call Trace: dump_stack+0x68/0x9f kasan_report_error+0x4c8/0x500 kasan_report+0x58/0x60 __asan_load4+0x61/0x80 efi_free_boot_services+0xae/0x24c start_kernel+0x527/0x562 x86_64_start_reservations+0x24/0x26 x86_64_start_kernel+0x157/0x17a start_cpu+0x5/0x14 The instruction at the given address is the first read from the memmap's memory, i.e. the read of md->type in efi_free_boot_services(). Note that the writes earlier in efi_arch_mem_reserve() don't splat because they're done through early_memremap()ed addresses. So, after memblock is gone, allocations should be done through the "normal" page allocator. Introduce a helper, efi_memmap_alloc() for this. Use it from efi_arch_mem_reserve() and from efi_free_boot_services() as well. Fixes: 4bc9f92e64c8 ("x86/efi-bgrt: Use efi_mem_reserve() to avoid copying image data") Signed-off-by: Nicolai Stange --- arch/x86/platform/efi/quirks.c | 4 ++-- drivers/firmware/efi/memmap.c | 38 ++++++++++++++++++++++++++++++++++++++ include/linux/efi.h | 1 + 3 files changed, 41 insertions(+), 2 deletions(-) diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c index 10aca63a50d7..30031d5293c4 100644 --- a/arch/x86/platform/efi/quirks.c +++ b/arch/x86/platform/efi/quirks.c @@ -214,7 +214,7 @@ void __init efi_arch_mem_reserve(phys_addr_t addr, u64 size) new_size = efi.memmap.desc_size * num_entries; - new_phys = memblock_alloc(new_size, 0); + new_phys = efi_memmap_alloc(num_entries); if (!new_phys) { pr_err("Could not allocate boot services memmap\n"); return; @@ -355,7 +355,7 @@ void __init efi_free_boot_services(void) } new_size = efi.memmap.desc_size * num_entries; - new_phys = memblock_alloc(new_size, 0); + new_phys = efi_memmap_alloc(num_entries); if (!new_phys) { pr_err("Failed to allocate new EFI memmap\n"); return; diff --git a/drivers/firmware/efi/memmap.c b/drivers/firmware/efi/memmap.c index f03ddecd232b..78686443cb37 100644 --- a/drivers/firmware/efi/memmap.c +++ b/drivers/firmware/efi/memmap.c @@ -9,6 +9,44 @@ #include #include #include +#include +#include + +static phys_addr_t __init __efi_memmap_alloc_early(unsigned long size) +{ + return memblock_alloc(size, 0); +} + +static phys_addr_t __init __efi_memmap_alloc_late(unsigned long size) +{ + unsigned int order = get_order(size); + struct page *p = alloc_pages(GFP_KERNEL, order); + + if (!p) + return 0; + + return PFN_PHYS(page_to_pfn(p)); +} + +/** + * efi_memmap_alloc - Allocate memory for the EFI memory map + * @num_entries: Number of entries in the allocated map. + * + * Depending on whether mm_init() has already been invoked or not, + * either memblock or "normal" page allocation is used. + * + * Returns the physical address of the allocated memory map on + * success, zero on failure. + */ +phys_addr_t __init efi_memmap_alloc(unsigned int num_entries) +{ + unsigned long size = num_entries * efi.memmap.desc_size; + + if (slab_is_available()) + return __efi_memmap_alloc_late(size); + + return __efi_memmap_alloc_early(size); +} /** * __efi_memmap_init - Common code for mapping the EFI memory map diff --git a/include/linux/efi.h b/include/linux/efi.h index a07a476178cd..0c5420208c40 100644 --- a/include/linux/efi.h +++ b/include/linux/efi.h @@ -950,6 +950,7 @@ static inline efi_status_t efi_query_variable_store(u32 attributes, #endif extern void __iomem *efi_lookup_mapped_addr(u64 phys_addr); +extern phys_addr_t __init efi_memmap_alloc(unsigned int num_entries); extern int __init efi_memmap_init_early(struct efi_memory_map_data *data); extern int __init efi_memmap_init_late(phys_addr_t addr, unsigned long size); extern void __init efi_memmap_unmap(void); -- 2.11.0