> -----Original Message----- > From: Jung-uk Kim <jkim@xxxxxxxxxxx> > Sent: Wednesday, June 10, 2020 4:46 PM > To: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>; Kaneda, Erik > <erik.kaneda@xxxxxxxxx> > Cc: Wysocki, Rafael J <rafael.j.wysocki@xxxxxxxxx>; Ard Biesheuvel > <ardb@xxxxxxxxxx>; dvyukov@xxxxxxxxxx; glider@xxxxxxxxxx; linux-arm- > kernel@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > lorenzo.pieralisi@xxxxxxx; mark.rutland@xxxxxxx; pcc@xxxxxxxxxx; > rjw@xxxxxxxxxxxxx; will@xxxxxxxxxx; stable@xxxxxxxxxxxxxxx; linux- > acpi@xxxxxxxxxxxxxxx; devel@xxxxxxxxxx > Subject: [Devel] Re: [PATCH] ACPICA: fix UBSAN warning using > __builtin_offsetof > > On 20. 6. 10., Nick Desaulniers wrote: > > On Wed, Jun 10, 2020 at 4:07 PM Kaneda, Erik <erik.kaneda@xxxxxxxxx> > wrote: > >> > >> +JKim (for FreeBSD's perspective) > >> > >>> -----Original Message----- > >>> From: Nick Desaulniers <ndesaulniers@xxxxxxxxxx> > >>> Sent: Monday, June 1, 2020 4:18 PM > >>> To: Moore, Robert <robert.moore@xxxxxxxxx>; Kaneda, Erik > >>> <erik.kaneda@xxxxxxxxx>; Wysocki, Rafael J > <rafael.j.wysocki@xxxxxxxxx>; > >>> Len Brown <lenb@xxxxxxxxxx> > >>> Cc: Ard Biesheuvel <ardb@xxxxxxxxxx>; dvyukov@xxxxxxxxxx; > >>> glider@xxxxxxxxxx; guohanjun@xxxxxxxxxx; linux-arm- > >>> kernel@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > >>> lorenzo.pieralisi@xxxxxxx; mark.rutland@xxxxxxx; > >>> ndesaulniers@xxxxxxxxxx; pcc@xxxxxxxxxx; rjw@xxxxxxxxxxxxx; > >>> will@xxxxxxxxxx; stable@xxxxxxxxxxxxxxx; linux-acpi@xxxxxxxxxxxxxxx; > >>> devel@xxxxxxxxxx > >>> 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 */ > > > > s/definiton/definition/ > > > >> + > >> +#ifndef offsetof > >> +#define offsetof(d,f) ACPI_PTR_DIFF (&(((d *) 0)->f), (void *) > 0) > >> +#endif > > > > If this header doesn't explicitly include <stddef.h> or > > <linux/stddef.h>, won't translation units that include > > <acpi/actypes.h> get different definitions of ACPI_OFFSET based on > > whether they explicitly or transitively included <stddef.h> before > > including <acpi/actypes.h>? Theoretically, a translation unit in the > > kernel could include actypes.h, have no includes of linux/stddef.h, > > then get UBSAN errors again from using this definition? > > > > I don't mind using offsetof in place of the builtin (since it > > typically will be implemented in terms of the builtin, or is at least > > for the case specific to the Linux kernel). But if it's used, we > > should include the header that defines it properly, and we should not > > use the host's <stddef.h> IMO. Is there a platform specific way to > > include the platform's stddef.h here? > > > > Maybe linux/stddef.h should be included in > > include/acpi/platform/aclinux.h, then include/acpi/platform/acenv.h > > included in include/acpi/actypes.h, such that ACPI_OFFSET is defined > > in terms of offsetof defined from that transitive dependency of > > headers? (or do we get a circular inclusion trying to do that?) > Hi, > Actually, I think we should let platform-specific acfoo.h decide what to > do here, i.e., That's a better solution. For Linux, it would look something like this: --- a/include/acpi/actypes.h +++ b/include/acpi/actypes.h @@ -508,10 +508,15 @@ 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_PHYSADDR_TO_PTR(i) ACPI_TO_POINTER(i) #define ACPI_PTR_TO_PHYSADDR(i) ACPI_TO_INTEGER(i) +/* Platforms may want to define their own ACPI_OFFSET */ + +#ifndef ACPI_OFFSET +#define ACPI_OFFSET(d, f) ACPI_PTR_DIFF (&(((d *) 0)->f), (void *) 0) +#endif + /* Optimizations for 4-character (32-bit) acpi_name manipulation */ #ifndef ACPI_MISALIGNMENT_NOT_SUPPORTED diff --git a/include/acpi/platform/aclinux.h b/include/acpi/platform/aclinux.h index 987e2af7c335..5d1ca6015fce 100644 --- a/include/acpi/platform/aclinux.h +++ b/include/acpi/platform/aclinux.h @@ -71,6 +71,11 @@ #undef ACPI_DEBUG_DEFAULT #define ACPI_DEBUG_DEFAULT (ACPI_LV_INFO | ACPI_LV_REPAIR) +/* Use gcc's builtin offset instead of the default */ + +#undef ACPI_OFFSET +#define ACPI_OFFSET(a,b) __builtin_offsetof(a,b) + #ifndef CONFIG_ACPI > > #ifndef ACPI_OFFSET > #define ACPI_OFFSET(d, f) ... > #endif > > Jung-uk Kim > > >> + > >> /* 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) > >> > >> Thanks, > >> Erik > >> > >>> 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 > > _______________________________________________ > Devel mailing list -- devel@xxxxxxxxxx > To unsubscribe send an email to devel-leave@xxxxxxxxxx > %(web_page_url)slistinfo%(cgiext)s/%(_internal_name)s
