On 20. 6. 10., Kaneda, Erik wrote:
+JKim (for FreeBSD's perspective)
-----Original Message----- From: Nick Desaulniers ndesaulniers@google.com Sent: Monday, June 1, 2020 4:18 PM To: Moore, Robert robert.moore@intel.com; Kaneda, Erik erik.kaneda@intel.com; Wysocki, Rafael J rafael.j.wysocki@intel.com; Len Brown lenb@kernel.org Cc: Ard Biesheuvel ardb@kernel.org; dvyukov@google.com; glider@google.com; guohanjun@huawei.com; linux-arm- kernel@lists.infradead.org; linux-kernel@vger.kernel.org; lorenzo.pieralisi@arm.com; mark.rutland@arm.com; ndesaulniers@google.com; pcc@google.com; rjw@rjwysocki.net; will@kernel.org; stable@vger.kernel.org; linux-acpi@vger.kernel.org; devel@acpica.org Subject: [PATCH] ACPICA: fix UBSAN warning using __builtin_offsetof
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
Hi,
Looks like the emulated offsetof macro ACPI_OFFSET is causing these. We can avoid this by using the compiler builtin, __builtin_offsetof.
This doesn't really fly because __builtin_offsetof is a compiler extension.
It looks like a lot of stddef.h files do this:
#define offsetof(a,b) __builtin_offset(a,b)
So does anyone have objections to ACPI_OFFSET being defined to offsetof()?
This will allow a host OS project project to use their own definitions of offsetof in place of ACPICA's. If they don't have a definition for offsetof, we can supply the old one as a fallback.
Here's a patch:
--- a/include/acpi/actypes.h +++ b/include/acpi/actypes.h @@ -504,11 +504,17 @@ typedef u64 acpi_integer; #define ACPI_SUB_PTR(t, a, b) ACPI_CAST_PTR (t, (ACPI_CAST_PTR (u8, (a)) - (acpi_size)(b))) #define ACPI_PTR_DIFF(a, b) ((acpi_size) (ACPI_CAST_PTR (u8, (a)) - ACPI_CAST_PTR (u8, (b))))
+/* Use an existing definiton for offsetof */
+#ifndef offsetof +#define offsetof(d,f) ACPI_PTR_DIFF (&(((d *) 0)->f), (void *) 0) +#endif
/* Pointer/Integer type conversions */
#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) offsetof (d,f) #define ACPI_PHYSADDR_TO_PTR(i) ACPI_TO_POINTER(i) #define ACPI_PTR_TO_PHYSADDR(i) ACPI_TO_INTEGER(i)
LGTM.
Jung-uk Kim
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@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
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