Will reported a UBSAN warning:
UBSAN: null-ptr-deref in arch/arm64/kernel/smp.c:596:6 member access within null pointer of type 'struct acpi_madt_generic_interrupt' CPU: 0 PID: 0 Comm: swapper Not tainted 5.7.0-rc6-00124-g96bc42ff0a82 #1 Call trace: dump_backtrace+0x0/0x384 show_stack+0x28/0x38 dump_stack+0xec/0x174 handle_null_ptr_deref+0x134/0x174 __ubsan_handle_type_mismatch_v1+0x84/0xa4 acpi_parse_gic_cpu_interface+0x60/0xe8 acpi_parse_entries_array+0x288/0x498 acpi_table_parse_entries_array+0x178/0x1b4 acpi_table_parse_madt+0xa4/0x110 acpi_parse_and_init_cpus+0x38/0x100 smp_init_cpus+0x74/0x258 setup_arch+0x350/0x3ec start_kernel+0x98/0x6f4
This is from the use of the ACPI_OFFSET in arch/arm64/include/asm/acpi.h. Replace its use with offsetof from include/linux/stddef.h which should implement the same logic using __builtin_offsetof, so that UBSAN wont warn.
Link: https://lore.kernel.org/lkml/20200521100952.GA5360@willie-the-truck/ Cc: stable@vger.kernel.org Reported-by: Will Deacon will@kernel.org Suggested-by: Ard Biesheuvel ardb@kernel.org Signed-off-by: Nick Desaulniers ndesaulniers@google.com --- Changes V1 -> V2: * Just fix one of the two warnings, specific to arm64. * Put warning in commit message.
arch/arm64/include/asm/acpi.h | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h index b263e239cb59..a45366c3909b 100644 --- a/arch/arm64/include/asm/acpi.h +++ b/arch/arm64/include/asm/acpi.h @@ -12,6 +12,7 @@ #include <linux/efi.h> #include <linux/memblock.h> #include <linux/psci.h> +#include <linux/stddef.h>
#include <asm/cputype.h> #include <asm/io.h> @@ -31,14 +32,14 @@ * is therefore used to delimit the MADT GICC structure minimum length * appropriately. */ -#define ACPI_MADT_GICC_MIN_LENGTH ACPI_OFFSET( \ +#define ACPI_MADT_GICC_MIN_LENGTH offsetof( \ struct acpi_madt_generic_interrupt, efficiency_class)
#define BAD_MADT_GICC_ENTRY(entry, end) \ (!(entry) || (entry)->header.length < ACPI_MADT_GICC_MIN_LENGTH || \ (unsigned long)(entry) + (entry)->header.length > (end))
-#define ACPI_MADT_GICC_SPE (ACPI_OFFSET(struct acpi_madt_generic_interrupt, \ +#define ACPI_MADT_GICC_SPE (offsetof(struct acpi_madt_generic_interrupt, \ spe_interrupt) + sizeof(u16))
/* Basic configuration for ACPI */