From: Ard Biesheuvel ard.biesheuvel@linaro.org
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 swt@techie.net Signed-off-by: Ard Biesheuvel ard.biesheuvel@linaro.org Cc: stable@vger.kernel.org # v4.9+ Cc: Ben Dooks ben.dooks@codethink.co.uk Cc: Dave Young dyoung@redhat.com Cc: Jarkko Sakkinen jarkko.sakkinen@linux.intel.com Cc: Jerry Snitselaar jsnitsel@redhat.com Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Lukas Wunner lukas@wunner.de Cc: Lyude Paul lyude@redhat.com Cc: Matthew Garrett mjg59@google.com Cc: Octavian Purdila octavian.purdila@intel.com Cc: Peter Jones pjones@redhat.com Cc: Peter Zijlstra peterz@infradead.org Cc: Thomas Gleixner tglx@linutronix.de 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 mingo@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/firmware/efi/efi.c | 3 +++ 1 file changed, 3 insertions(+)
--- a/drivers/firmware/efi/efi.c +++ b/drivers/firmware/efi/efi.c @@ -243,6 +243,9 @@ 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) {