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authorDave Young2017-06-09 08:45:58 +0000
committerIngo Molnar2017-06-09 14:50:11 +0200
commit792ef14df5c585c19b2831673a077504a09e5203 (patch)
tree37c465fd2bf1c0ae0959dc73a512a73c1ea4dd78
parent0d22df90c7eadeaf852caca49ae8df9b2c3075a4 (diff)
efi: Fix boot panic because of invalid BGRT image address
Maniaxx reported a kernel boot crash in the EFI code, which I emulated by using same invalid phys addr in code: BUG: unable to handle kernel paging request at ffffffffff280001 IP: efi_bgrt_init+0xfb/0x153 ... Call Trace: ? bgrt_init+0xbc/0xbc acpi_parse_bgrt+0xe/0x12 acpi_table_parse+0x89/0xb8 acpi_boot_init+0x445/0x4e2 ? acpi_parse_x2apic+0x79/0x79 ? dmi_ignore_irq0_timer_override+0x33/0x33 setup_arch+0xb63/0xc82 ? early_idt_handler_array+0x120/0x120 start_kernel+0xb7/0x443 ? early_idt_handler_array+0x120/0x120 x86_64_start_reservations+0x29/0x2b x86_64_start_kernel+0x154/0x177 secondary_startup_64+0x9f/0x9f There is also a similar bug filed in bugzilla.kernel.org: https://bugzilla.kernel.org/show_bug.cgi?id=195633 The crash is caused by this commit: 7b0a911478c7 efi/x86: Move the EFI BGRT init code to early init code The root cause is the firmware on those machines provides invalid BGRT image addresses. In a kernel before above commit BGRT initializes late and uses ioremap() to map the image address. Ioremap validates the address, if it is not a valid physical address ioremap() just fails and returns. However in current kernel EFI BGRT initializes early and uses early_memremap() which does not validate the image address, and kernel panic happens. According to ACPI spec the BGRT image address should fall into EFI_BOOT_SERVICES_DATA, see the section 5.2.22.4 of below document: http://www.uefi.org/sites/default/files/resources/ACPI_6_1.pdf Fix this issue by validating the image address in efi_bgrt_init(). If the image address does not fall into any EFI_BOOT_SERVICES_DATA areas we just bail out with a warning message. Reported-by: Maniaxx <tripleshiftone@gmail.com> Signed-off-by: Dave Young <dyoung@redhat.com> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matt Fleming <matt@codeblueprint.co.uk> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-efi@vger.kernel.org Fixes: 7b0a911478c7 ("efi/x86: Move the EFI BGRT init code to early init code") Link: http://lkml.kernel.org/r/20170609084558.26766-2-ard.biesheuvel@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
-rw-r--r--drivers/firmware/efi/efi-bgrt.c26
1 files changed, 25 insertions, 1 deletions
diff --git a/drivers/firmware/efi/efi-bgrt.c b/drivers/firmware/efi/efi-bgrt.c
index 8bf27323f7a3..b58233e4ed71 100644
--- a/drivers/firmware/efi/efi-bgrt.c
+++ b/drivers/firmware/efi/efi-bgrt.c
@@ -27,6 +27,26 @@ struct bmp_header {
u32 size;
} __packed;
+static bool efi_bgrt_addr_valid(u64 addr)
+{
+ efi_memory_desc_t *md;
+
+ for_each_efi_memory_desc(md) {
+ u64 size;
+ u64 end;
+
+ if (md->type != EFI_BOOT_SERVICES_DATA)
+ continue;
+
+ size = md->num_pages << EFI_PAGE_SHIFT;
+ end = md->phys_addr + size;
+ if (addr >= md->phys_addr && addr < end)
+ return true;
+ }
+
+ return false;
+}
+
void __init efi_bgrt_init(struct acpi_table_header *table)
{
void *image;
@@ -36,7 +56,7 @@ void __init efi_bgrt_init(struct acpi_table_header *table)
if (acpi_disabled)
return;
- if (!efi_enabled(EFI_BOOT))
+ if (!efi_enabled(EFI_MEMMAP))
return;
if (table->length < sizeof(bgrt_tab)) {
@@ -65,6 +85,10 @@ void __init efi_bgrt_init(struct acpi_table_header *table)
goto out;
}
+ if (!efi_bgrt_addr_valid(bgrt->image_address)) {
+ pr_notice("Ignoring BGRT: invalid image address\n");
+ goto out;
+ }
image = early_memremap(bgrt->image_address, sizeof(bmp_header));
if (!image) {
pr_notice("Ignoring BGRT: failed to map image header memory\n");