On Mon, Apr 10, 2017 at 11:30:38AM +0100, Ard Biesheuvel wrote:
> As reported by James, Catalin and Mark, commit e69176d68d26
> ("ef/libstub/arm/arm64: Randomize the base of the UEFI rt services
> region") results in a crash in the firmware regardless of whether KASLR
> is in effect or not, and whether the firmware implements EFI_RNG_PROTOCOL
> or not.
>
> Mark has identified the root cause to be the inappropriate use of
> TASK_SIZE in the stub, which arm64 defines as
>
> #define TASK_SIZE (test_thread_flag(TIF_32BIT) ? \
> TASK_SIZE_32 : TASK_SIZE_64)
>
> and testing thread flags at this point results in the dereference of
> pointers in uninitialized structures.
>
> So instead, introduce a preprocessor symbol EFI_RT_VIRTUAL_LIMIT and
> define it to TASK_SIZE_64 on arm64 and TASK_SIZE on ARM, both of which
> are compile time constants. Also, change the 'headroom' variable to
> static const to force an error if this changes in the future.
>
> Cc: James Morse <james.morse@xxxxxxx>
> Cc: Mark Rutland <mark.rutland@xxxxxxx>
> Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
> Cc: Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
It works for me as well:
Tested-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Thanks Ard and Mark.
--
Catalin
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