Commit-ID: 09503379dc99535b1bbfa51aa1aeef340f5d82ec Gitweb: http://git.kernel.org/tip/09503379dc99535b1bbfa51aa1aeef340f5d82ec Author: Matt Fleming <matt.fleming@xxxxxxxxx> AuthorDate: Thu, 13 Feb 2014 17:17:54 +0000 Committer: Matt Fleming <matt.fleming@xxxxxxxxx> CommitDate: Fri, 14 Feb 2014 10:07:15 +0000 x86/efi: Check status field to validate BGRT header Madper reported seeing the following crash, BUG: unable to handle kernel paging request at ffffffffff340003 IP: [<ffffffff81d85ba4>] efi_bgrt_init+0x9d/0x133 Call Trace: [<ffffffff81d8525d>] efi_late_init+0x9/0xb [<ffffffff81d68f59>] start_kernel+0x436/0x450 [<ffffffff81d6892c>] ? repair_env_string+0x5c/0x5c [<ffffffff81d68120>] ? early_idt_handlers+0x120/0x120 [<ffffffff81d685de>] x86_64_start_reservations+0x2a/0x2c [<ffffffff81d6871e>] x86_64_start_kernel+0x13e/0x14d This is caused because the layout of the ACPI BGRT header on this system doesn't match the definition from the ACPI spec, and so we get a bogus physical address when dereferencing ->image_address in efi_bgrt_init(). Luckily the status field in the BGRT header clearly marks it as invalid, so we can check that field and skip BGRT initialisation. Reported-by: Madper Xie <cxie@xxxxxxxxxx> Suggested-by: Toshi Kani <toshi.kani@xxxxxx> Cc: "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx> Cc: Matthew Garrett <mjg59@xxxxxxxxxxxxx> Cc: Josh Triplett <josh@xxxxxxxxxxxxxxxx> Signed-off-by: Matt Fleming <matt.fleming@xxxxxxxxx> --- arch/x86/platform/efi/efi-bgrt.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/platform/efi/efi-bgrt.c b/arch/x86/platform/efi/efi-bgrt.c index 4df9591..f15103d 100644 --- a/arch/x86/platform/efi/efi-bgrt.c +++ b/arch/x86/platform/efi/efi-bgrt.c @@ -42,7 +42,7 @@ void __init efi_bgrt_init(void) if (bgrt_tab->header.length < sizeof(*bgrt_tab)) return; - if (bgrt_tab->version != 1) + if (bgrt_tab->version != 1 || bgrt_tab->status != 1) return; if (bgrt_tab->image_type != 0 || !bgrt_tab->image_address) return; -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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