Hey Nick,
On Tue, Jun 02, 2020 at 11:46:31AM -0700, Nick Desaulniers wrote:
On Mon, Jun 1, 2020 at 5:03 PM Kaneda, Erik [off-list ref] wrote:
quoted
quoted
Will reported UBSAN warnings:
UBSAN: null-ptr-deref in drivers/acpi/acpica/tbfadt.c:459:37
UBSAN: null-ptr-deref in arch/arm64/kernel/smp.c:596:6
Looks like the emulated offsetof macro ACPI_OFFSET is causing these. We
can avoid this by using the compiler builtin, __builtin_offsetof.
I'll take a look at this tomorrow
quoted
The non-kernel runtime of UBSAN would print:
runtime error: member access within null pointer of type for this macro.
actypes.h is owned by ACPICA so we typically do not allow compiler-specific
extensions because the code is intended to be compiled using the C99 standard
without compiler extensions. We could allow this sort of thing in a Linux-specific
header file like include/acpi/platform/aclinux.h but I'll take a look at the error as well..
If I'm not allowed to touch that header, it looks like I can include
<linux/stddef.h> (rather than my host's <stddef.h>) to get a
definition of `offsetof` thats implemented in terms of
`__builtin_offsetof`. I should be able to use that to replace uses of
ACPI_OFFSET. Are any of these off limits?
It's not so much about not being allowed to touch the header, but rather
that the kernel imports the code from a different project:
https://acpica.org/community
$ grep -rn ACPI_OFFSET
arch/arm64/include/asm/acpi.h:34:#define ACPI_MADT_GICC_MIN_LENGTH
ACPI_OFFSET( \
arch/arm64/include/asm/acpi.h:41:#define ACPI_MADT_GICC_SPE
(ACPI_OFFSET(struct acpi_madt_generic_interrupt, \
I'm happy to take patches to the stuff under arch/arm64/, fwiw.
Will
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