path: root/drivers/firmware/efi/memmap.c
diff options
authorNicolai Stange <nicstange@gmail.com>2017-01-05 13:51:29 +0100
committerIngo Molnar <mingo@kernel.org>2017-01-07 08:58:07 +0100
commit20b1e22d01a4b0b11d3a1066e9feb04be38607ec (patch)
tree614e00a43b1e0d6af54685d52e12b106bc5cae23 /drivers/firmware/efi/memmap.c
parentabfb7b686a3e5be27bf81db62f9c5c895b76f5d1 (diff)
x86/efi: Don't allocate memmap through memblock after mm_init()
With the following 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(), efi_free_boot_services() and, for the sake of consistency, from efi_fake_memmap() as well. Note that for the latter, the memmap allocations cease to be page aligned. This isn't needed though. Tested-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Nicolai Stange <nicstange@gmail.com> Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: <stable@vger.kernel.org> # v4.9 Cc: Dave Young <dyoung@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matt Fleming <matt@codeblueprint.co.uk> Cc: Mika Penttilä <mika.penttila@nextfour.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-efi@vger.kernel.org Fixes: 4bc9f92e64c8 ("x86/efi-bgrt: Use efi_mem_reserve() to avoid copying image data") Link: http://lkml.kernel.org/r/20170105125130.2815-1-nicstange@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'drivers/firmware/efi/memmap.c')
1 files changed, 38 insertions, 0 deletions
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 <linux/efi.h>
#include <linux/io.h>
#include <asm/early_ioremap.h>
+#include <linux/memblock.h>
+#include <linux/slab.h>
+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