From ee7ee6cfc3afceec73419a125879bc9d5404d014 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Wed, 2 Oct 2019 18:58:59 +0200 Subject: [PATCH] efivar/ssdt: Don't iterate over EFI vars if no SSDT override was specified commit c05f8f92b701576b615f30aac31fabdc0648649b upstream. The kernel command line option efivar_ssdt= allows the name to be specified of an EFI variable containing an ACPI SSDT table that should be loaded into memory by the OS, and treated as if it was provided by the firmware. Currently, that code will always iterate over the EFI variables and compare each name with the provided name, even if the command line option wasn't set to begin with. So bail early when no variable name was provided. This works around a boot regression on the 2012 Mac Pro, as reported by Scott. Tested-by: Scott Talbert Signed-off-by: Ard Biesheuvel Cc: # v4.9+ Cc: Ben Dooks Cc: Dave Young Cc: Jarkko Sakkinen Cc: Jerry Snitselaar Cc: Linus Torvalds Cc: Lukas Wunner Cc: Lyude Paul Cc: Matthew Garrett Cc: Octavian Purdila Cc: Peter Jones Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-efi@vger.kernel.org Cc: linux-integrity@vger.kernel.org Fixes: 475fb4e8b2f4 ("efi / ACPI: load SSTDs from EFI variables") Link: https://lkml.kernel.org/r/20191002165904.8819-3-ard.biesheuvel@linaro.org Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- drivers/firmware/efi/efi.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c index 2a29dd9..d54fca9 100644 --- a/drivers/firmware/efi/efi.c +++ b/drivers/firmware/efi/efi.c @@ -281,6 +281,9 @@ static __init int efivar_ssdt_load(void) void *data; int ret; + if (!efivar_ssdt[0]) + return 0; + ret = efivar_init(efivar_ssdt_iter, &entries, true, &entries); list_for_each_entry_safe(entry, aux, &entries, list) { -- 2.7.4