On Mon, Jun 1, 2020 at 4:18 PM Nick Desaulniers <ndesaulniers@xxxxxxxxxx> wrote: > > 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. Would it be better to s/ACPI_OFFSET/offsetof/g the existing users of this macro and remove it? It looks like offsetof is already being used pervasively in the kernel, and its definition comes from <linux/stddef.h>. Peter Peter > The non-kernel runtime of UBSAN would print: > runtime error: member access within null pointer of type > for this macro. > > Link: https://lore.kernel.org/lkml/20200521100952.GA5360@willie-the-truck/ > Cc: stable@xxxxxxxxxxxxxxx > Reported-by: Will Deacon <will@xxxxxxxxxx> > Suggested-by: Ard Biesheuvel <ardb@xxxxxxxxxx> > Signed-off-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx> > --- > include/acpi/actypes.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/include/acpi/actypes.h b/include/acpi/actypes.h > index 4defed58ea33..04359c70b198 100644 > --- a/include/acpi/actypes.h > +++ b/include/acpi/actypes.h > @@ -508,7 +508,7 @@ typedef u64 acpi_integer; > > #define ACPI_TO_POINTER(i) ACPI_CAST_PTR (void, (acpi_size) (i)) > #define ACPI_TO_INTEGER(p) ACPI_PTR_DIFF (p, (void *) 0) > -#define ACPI_OFFSET(d, f) ACPI_PTR_DIFF (&(((d *) 0)->f), (void *) 0) > +#define ACPI_OFFSET(d, f) __builtin_offsetof(d, f) > #define ACPI_PHYSADDR_TO_PTR(i) ACPI_TO_POINTER(i) > #define ACPI_PTR_TO_PHYSADDR(i) ACPI_TO_INTEGER(i) > > -- > 2.27.0.rc2.251.g90737beb825-goog >
