From 484a418d075488c6999528247cc711d12c373447 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Mon, 13 Jan 2020 18:22:45 +0100 Subject: [PATCH] efi: Fix handling of multiple efi_fake_mem= entries Dave noticed that when specifying multiple efi_fake_mem= entries only the last entry was successfully being reflected in the efi memory map. This is due to the fact that the efi_memmap_insert() is being called multiple times, but on successive invocations the insertion should be applied to the last new memmap rather than the original map at efi_fake_memmap() entry. Rework efi_fake_memmap() to install the new memory map after each efi_fake_mem= entry is parsed. This also fixes an issue in efi_fake_memmap() that caused it to litter emtpy entries into the end of the efi memory map. An empty entry causes efi_memmap_insert() to attempt more memmap splits / copies than efi_memmap_split_count() accounted for when sizing the new map. When that happens efi_memmap_insert() may overrun its allocation, and if you are lucky will spill over to an unmapped page leading to crash signature like the following rather than silent corruption: BUG: unable to handle page fault for address: ffffffffff281000 [..] RIP: 0010:efi_memmap_insert+0x11d/0x191 [..] Call Trace: ? bgrt_init+0xbe/0xbe ? efi_arch_mem_reserve+0x1cb/0x228 ? acpi_parse_bgrt+0xa/0xd ? acpi_table_parse+0x86/0xb8 ? acpi_boot_init+0x494/0x4e3 ? acpi_parse_x2apic+0x87/0x87 ? setup_acpi_sci+0xa2/0xa2 ? setup_arch+0x8db/0x9e1 ? start_kernel+0x6a/0x547 ? secondary_startup_64+0xb6/0xc0 Commit af1648984828 "x86/efi: Update e820 with reserved EFI boot services data to fix kexec breakage" introduced more occurrences where efi_memmap_insert() is invoked after an efi_fake_mem= configuration has been parsed. Previously the side effects of vestigial empty entries were benign, but with commit af1648984828 that follow-on efi_memmap_insert() invocation triggers efi_memmap_insert() overruns. Reported-by: Dave Young Signed-off-by: Dan Williams Signed-off-by: Ard Biesheuvel Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20191231014630.GA24942@dhcp-128-65.nay.redhat.com Link: https://lore.kernel.org/r/20200113172245.27925-14-ardb@kernel.org --- drivers/firmware/efi/fake_mem.c | 31 ++++++++++++++++--------------- drivers/firmware/efi/memmap.c | 2 +- include/linux/efi.h | 2 ++ 3 files changed, 19 insertions(+), 16 deletions(-) diff --git a/drivers/firmware/efi/fake_mem.c b/drivers/firmware/efi/fake_mem.c index a8d20568d532..6e0f34a38171 100644 --- a/drivers/firmware/efi/fake_mem.c +++ b/drivers/firmware/efi/fake_mem.c @@ -34,25 +34,16 @@ static int __init cmp_fake_mem(const void *x1, const void *x2) return 0; } -void __init efi_fake_memmap(void) +static void __init efi_fake_range(struct efi_mem_range *efi_range) { struct efi_memory_map_data data = { 0 }; int new_nr_map = efi.memmap.nr_map; efi_memory_desc_t *md; void *new_memmap; - int i; - - if (!efi_enabled(EFI_MEMMAP) || !nr_fake_mem) - return; /* count up the number of EFI memory descriptor */ - for (i = 0; i < nr_fake_mem; i++) { - for_each_efi_memory_desc(md) { - struct range *r = &efi_fake_mems[i].range; - - new_nr_map += efi_memmap_split_count(md, r); - } - } + for_each_efi_memory_desc(md) + new_nr_map += efi_memmap_split_count(md, &efi_range->range); /* allocate memory for new EFI memmap */ if (efi_memmap_alloc(new_nr_map, &data) != 0) @@ -61,17 +52,27 @@ void __init efi_fake_memmap(void) /* create new EFI memmap */ new_memmap = early_memremap(data.phys_map, data.size); if (!new_memmap) { - memblock_free(data.phys_map, data.size); + __efi_memmap_free(data.phys_map, data.size, data.flags); return; } - for (i = 0; i < nr_fake_mem; i++) - efi_memmap_insert(&efi.memmap, new_memmap, &efi_fake_mems[i]); + efi_memmap_insert(&efi.memmap, new_memmap, efi_range); /* swap into new EFI memmap */ early_memunmap(new_memmap, data.size); efi_memmap_install(&data); +} + +void __init efi_fake_memmap(void) +{ + int i; + + if (!efi_enabled(EFI_MEMMAP) || !nr_fake_mem) + return; + + for (i = 0; i < nr_fake_mem; i++) + efi_fake_range(&efi_fake_mems[i]); /* print new EFI memmap */ efi_print_memmap(); diff --git a/drivers/firmware/efi/memmap.c b/drivers/firmware/efi/memmap.c index 501672166502..2ff1883dc788 100644 --- a/drivers/firmware/efi/memmap.c +++ b/drivers/firmware/efi/memmap.c @@ -29,7 +29,7 @@ static phys_addr_t __init __efi_memmap_alloc_late(unsigned long size) return PFN_PHYS(page_to_pfn(p)); } -static void __init __efi_memmap_free(u64 phys, unsigned long size, unsigned long flags) +void __init __efi_memmap_free(u64 phys, unsigned long size, unsigned long flags) { if (flags & EFI_MEMMAP_MEMBLOCK) { if (slab_is_available()) diff --git a/include/linux/efi.h b/include/linux/efi.h index adbe421835c1..7efd7072cca5 100644 --- a/include/linux/efi.h +++ b/include/linux/efi.h @@ -976,6 +976,8 @@ extern void __iomem *efi_lookup_mapped_addr(u64 phys_addr); extern int __init efi_memmap_alloc(unsigned int num_entries, struct efi_memory_map_data *data); +extern void __efi_memmap_free(u64 phys, unsigned long size, + unsigned long flags); 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); -- 2.45.2