| Message ID | 20230202223653.never.473-kees@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm64: Support Clang UBSAN trap codes for better reporting | expand |
On Thu, Feb 2, 2023 at 2:37 PM Kees Cook <keescook@chromium.org> wrote: > > On arm64, Clang encodes the UBSAN check type in the esr. Extract this > and actually report UBSAN traps with some specificity when building with > CONFIG_UBSAN_TRAP. Before: > > Internal error: BRK handler: 00000000f20003e8 [#1] PREEMPT SMP > > After: > > Internal error: UBSAN: shift out of bounds: 00000000f2005514 [#1] PREEMPT SMP > This is really great ! When I brought up the opaque error messages just a few hours ago, I didn't imagine you'd have a solution so quickly! I really appreciate your lightning fast effort here! Really, thanks so much! I think this will have a big impact for folks running into these new bug catchers. -john
On Thu, Feb 02, 2023 at 10:36:57PM +0000, Kees Cook wrote: > On arm64, Clang encodes the UBSAN check type in the esr. Extract this > and actually report UBSAN traps with some specificity when building with > CONFIG_UBSAN_TRAP. Before: Really minor nit, but could we mention CONFIG_UBSAN_TRAP at the start, e.g. change that first sentence to: | When CONFIG_UBSAN_TRAP=y on arm64, Clang encodes the UBSAN check type into a | BRK immediate, which is reported in the ESR. I was initially confused since I was aware that there are usually direct function calls for the reporting. Other than that, this looks fine to me, and regardless of the above: Acked-by: Mark Rutland <mark.rutland@arm.com> Mark. > Internal error: BRK handler: 00000000f20003e8 [#1] PREEMPT SMP > > After: > > Internal error: UBSAN: shift out of bounds: 00000000f2005514 [#1] PREEMPT SMP > > Cc: Catalin Marinas <catalin.marinas@arm.com> > Cc: Will Deacon <will@kernel.org> > Cc: Mark Rutland <mark.rutland@arm.com> > Cc: John Stultz <jstultz@google.com> > Cc: Yongqin Liu <yongqin.liu@linaro.org> > Cc: Sami Tolvanen <samitolvanen@google.com> > Cc: Ard Biesheuvel <ardb@kernel.org> > Cc: Yury Norov <yury.norov@gmail.com> > Cc: Andrey Konovalov <andreyknvl@gmail.com> > Cc: Marco Elver <elver@google.com> > Cc: linux-arm-kernel@lists.infradead.org > Cc: llvm@lists.linux.dev > Signed-off-by: Kees Cook <keescook@chromium.org> > --- > arch/arm64/include/asm/brk-imm.h | 2 ++ > arch/arm64/kernel/traps.c | 21 +++++++++++++ > include/linux/ubsan.h | 9 ++++++ > lib/Makefile | 2 -- > lib/ubsan.c | 54 ++++++++++++++++++++++++++++++++ > lib/ubsan.h | 28 +++++++++++++++++ > 6 files changed, 114 insertions(+), 2 deletions(-) > create mode 100644 include/linux/ubsan.h > > diff --git a/arch/arm64/include/asm/brk-imm.h b/arch/arm64/include/asm/brk-imm.h > index 6e000113e508..3f0f0d03268b 100644 > --- a/arch/arm64/include/asm/brk-imm.h > +++ b/arch/arm64/include/asm/brk-imm.h > @@ -28,6 +28,8 @@ > #define BUG_BRK_IMM 0x800 > #define KASAN_BRK_IMM 0x900 > #define KASAN_BRK_MASK 0x0ff > +#define UBSAN_BRK_IMM 0x5500 > +#define UBSAN_BRK_MASK 0x00ff > > #define CFI_BRK_IMM_TARGET GENMASK(4, 0) > #define CFI_BRK_IMM_TYPE GENMASK(9, 5) > diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c > index 4c0caa589e12..87f42eb1c950 100644 > --- a/arch/arm64/kernel/traps.c > +++ b/arch/arm64/kernel/traps.c > @@ -26,6 +26,7 @@ > #include <linux/syscalls.h> > #include <linux/mm_types.h> > #include <linux/kasan.h> > +#include <linux/ubsan.h> > #include <linux/cfi.h> > > #include <asm/atomic.h> > @@ -1074,6 +1075,19 @@ static struct break_hook kasan_break_hook = { > }; > #endif > > +#ifdef CONFIG_UBSAN_TRAP > +static int ubsan_handler(struct pt_regs *regs, unsigned long esr) > +{ > + die(report_ubsan_failure(regs, esr & UBSAN_BRK_MASK), regs, esr); > + return DBG_HOOK_HANDLED; > +} > + > +static struct break_hook ubsan_break_hook = { > + .fn = ubsan_handler, > + .imm = UBSAN_BRK_IMM, > + .mask = UBSAN_BRK_MASK, > +}; > +#endif > > #define esr_comment(esr) ((esr) & ESR_ELx_BRK64_ISS_COMMENT_MASK) > > @@ -1091,6 +1105,10 @@ int __init early_brk64(unsigned long addr, unsigned long esr, > #ifdef CONFIG_KASAN_SW_TAGS > if ((esr_comment(esr) & ~KASAN_BRK_MASK) == KASAN_BRK_IMM) > return kasan_handler(regs, esr) != DBG_HOOK_HANDLED; > +#endif > +#ifdef CONFIG_UBSAN_TRAP > + if ((esr_comment(esr) & ~UBSAN_BRK_MASK) == UBSAN_BRK_IMM) > + return ubsan_handler(regs, esr) != DBG_HOOK_HANDLED; > #endif > return bug_handler(regs, esr) != DBG_HOOK_HANDLED; > } > @@ -1104,6 +1122,9 @@ void __init trap_init(void) > register_kernel_break_hook(&fault_break_hook); > #ifdef CONFIG_KASAN_SW_TAGS > register_kernel_break_hook(&kasan_break_hook); > +#endif > +#ifdef CONFIG_UBSAN_TRAP > + register_kernel_break_hook(&ubsan_break_hook); > #endif > debug_traps_init(); > } > diff --git a/include/linux/ubsan.h b/include/linux/ubsan.h > new file mode 100644 > index 000000000000..bff7445498de > --- /dev/null > +++ b/include/linux/ubsan.h > @@ -0,0 +1,9 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > +#ifndef _LINUX_UBSAN_H > +#define _LINUX_UBSAN_H > + > +#ifdef CONFIG_UBSAN_TRAP > +const char *report_ubsan_failure(struct pt_regs *regs, u32 check_type); > +#endif > + > +#endif > diff --git a/lib/Makefile b/lib/Makefile > index 4d9461bfea42..81b988bf9448 100644 > --- a/lib/Makefile > +++ b/lib/Makefile > @@ -340,9 +340,7 @@ quiet_cmd_build_OID_registry = GEN $@ > clean-files += oid_registry_data.c > > obj-$(CONFIG_UCS2_STRING) += ucs2_string.o > -ifneq ($(CONFIG_UBSAN_TRAP),y) > obj-$(CONFIG_UBSAN) += ubsan.o > -endif > > UBSAN_SANITIZE_ubsan.o := n > KASAN_SANITIZE_ubsan.o := n > diff --git a/lib/ubsan.c b/lib/ubsan.c > index 60c7099857a0..98a671ec56e9 100644 > --- a/lib/ubsan.c > +++ b/lib/ubsan.c > @@ -18,6 +18,58 @@ > > #include "ubsan.h" > > +#ifdef CONFIG_UBSAN_TRAP > +const char *report_ubsan_failure(struct pt_regs *regs, u32 check_type) > +{ > + switch (check_type) { > + case ubsan_add_overflow: > + return "UBSAN: addition overflow"; > + case ubsan_builtin_unreachable: > + return "UBSAN: unreachable code"; > + case ubsan_cfi_check_fail: > + return "UBSAN: CFI failure"; > + case ubsan_divrem_overflow: > + return "UBSAN: divide/remainder overflow"; > + case ubsan_function_type_mismatch: > + return "UBSAN: function type mismatch"; > + case ubsan_implicit_conversion: > + return "UBSAN: implicit conversion"; > + case ubsan_invalid_builtin: > + return "UBSAN: invalid builtin"; > + case ubsan_invalid_objc_cast: > + return "UBSAN: invalid object cast"; > + case ubsan_load_invalid_value: > + return "UBSAN: loading invalid value"; > + case ubsan_missing_return: > + return "UBSAN: missing return"; > + case ubsan_mul_overflow: > + return "UBSAN: multiplication overflow"; > + case ubsan_negate_overflow: > + return "UBSAN: negation overflow"; > + case ubsan_nonnull_arg: > + return "UBSAN: non-NULL argument"; > + case ubsan_nonnull_return: > + return "UBSAN: non-NULL return"; > + case ubsan_out_of_bounds: > + return "UBSAN: array index out of bounds"; > + case ubsan_pointer_overflow: > + return "UBSAN: pointer overflow"; > + case ubsan_shift_out_of_bounds: > + return "UBSAN: shift out of bounds"; > + case ubsan_sub_overflow: > + return "UBSAN: subtraction overflow"; > + case ubsan_type_mismatch: > + return "UBSAN: type mismatch"; > + case ubsan_alignment_assumption: > + return "UBSAN: alignment assumption"; > + case ubsan_vla_bound_not_positive: > + return "UBSAN: VLA bounds not positive"; > + default: > + return "UBSAN: unknown failure"; > + } > +} > + > +#else > static const char * const type_check_kinds[] = { > "load of", > "store to", > @@ -384,3 +436,5 @@ void __ubsan_handle_alignment_assumption(void *_data, unsigned long ptr, > ubsan_epilogue(); > } > EXPORT_SYMBOL(__ubsan_handle_alignment_assumption); > + > +#endif /* !CONFIG_UBSAN_TRAP */ > diff --git a/lib/ubsan.h b/lib/ubsan.h > index 9a0b71c5ff9f..9c7f00f550f5 100644 > --- a/lib/ubsan.h > +++ b/lib/ubsan.h > @@ -2,6 +2,34 @@ > #ifndef _LIB_UBSAN_H > #define _LIB_UBSAN_H > > +enum ubsan_checks { > + ubsan_add_overflow, > + ubsan_builtin_unreachable, > + ubsan_cfi_check_fail, > + ubsan_divrem_overflow, > + ubsan_dynamic_type_cache_miss, > + ubsan_float_cast_overflow, > + ubsan_function_type_mismatch, > + ubsan_implicit_conversion, > + ubsan_invalid_builtin, > + ubsan_invalid_objc_cast, > + ubsan_load_invalid_value, > + ubsan_missing_return, > + ubsan_mul_overflow, > + ubsan_negate_overflow, > + ubsan_nullability_arg, > + ubsan_nullability_return, > + ubsan_nonnull_arg, > + ubsan_nonnull_return, > + ubsan_out_of_bounds, > + ubsan_pointer_overflow, > + ubsan_shift_out_of_bounds, > + ubsan_sub_overflow, > + ubsan_type_mismatch, > + ubsan_alignment_assumption, > + ubsan_vla_bound_not_positive, > +}; > + > enum { > type_kind_int = 0, > type_kind_float = 1, > -- > 2.34.1 >
On Thu, 2 Feb 2023 at 23:37, Kees Cook <keescook@chromium.org> wrote: > > On arm64, Clang encodes the UBSAN check type in the esr. Extract this > and actually report UBSAN traps with some specificity when building with > CONFIG_UBSAN_TRAP. Before: > > Internal error: BRK handler: 00000000f20003e8 [#1] PREEMPT SMP > > After: > > Internal error: UBSAN: shift out of bounds: 00000000f2005514 [#1] PREEMPT SMP > > Cc: Catalin Marinas <catalin.marinas@arm.com> > Cc: Will Deacon <will@kernel.org> > Cc: Mark Rutland <mark.rutland@arm.com> > Cc: John Stultz <jstultz@google.com> > Cc: Yongqin Liu <yongqin.liu@linaro.org> > Cc: Sami Tolvanen <samitolvanen@google.com> > Cc: Ard Biesheuvel <ardb@kernel.org> > Cc: Yury Norov <yury.norov@gmail.com> > Cc: Andrey Konovalov <andreyknvl@gmail.com> > Cc: Marco Elver <elver@google.com> > Cc: linux-arm-kernel@lists.infradead.org > Cc: llvm@lists.linux.dev > Signed-off-by: Kees Cook <keescook@chromium.org> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> One nit below > --- > arch/arm64/include/asm/brk-imm.h | 2 ++ > arch/arm64/kernel/traps.c | 21 +++++++++++++ > include/linux/ubsan.h | 9 ++++++ > lib/Makefile | 2 -- > lib/ubsan.c | 54 ++++++++++++++++++++++++++++++++ > lib/ubsan.h | 28 +++++++++++++++++ > 6 files changed, 114 insertions(+), 2 deletions(-) > create mode 100644 include/linux/ubsan.h > > diff --git a/arch/arm64/include/asm/brk-imm.h b/arch/arm64/include/asm/brk-imm.h > index 6e000113e508..3f0f0d03268b 100644 > --- a/arch/arm64/include/asm/brk-imm.h > +++ b/arch/arm64/include/asm/brk-imm.h > @@ -28,6 +28,8 @@ > #define BUG_BRK_IMM 0x800 > #define KASAN_BRK_IMM 0x900 > #define KASAN_BRK_MASK 0x0ff > +#define UBSAN_BRK_IMM 0x5500 > +#define UBSAN_BRK_MASK 0x00ff > > #define CFI_BRK_IMM_TARGET GENMASK(4, 0) > #define CFI_BRK_IMM_TYPE GENMASK(9, 5) > diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c > index 4c0caa589e12..87f42eb1c950 100644 > --- a/arch/arm64/kernel/traps.c > +++ b/arch/arm64/kernel/traps.c > @@ -26,6 +26,7 @@ > #include <linux/syscalls.h> > #include <linux/mm_types.h> > #include <linux/kasan.h> > +#include <linux/ubsan.h> > #include <linux/cfi.h> > > #include <asm/atomic.h> > @@ -1074,6 +1075,19 @@ static struct break_hook kasan_break_hook = { > }; > #endif > > +#ifdef CONFIG_UBSAN_TRAP > +static int ubsan_handler(struct pt_regs *regs, unsigned long esr) > +{ > + die(report_ubsan_failure(regs, esr & UBSAN_BRK_MASK), regs, esr); > + return DBG_HOOK_HANDLED; > +} > + > +static struct break_hook ubsan_break_hook = { > + .fn = ubsan_handler, > + .imm = UBSAN_BRK_IMM, > + .mask = UBSAN_BRK_MASK, > +}; > +#endif > > #define esr_comment(esr) ((esr) & ESR_ELx_BRK64_ISS_COMMENT_MASK) > > @@ -1091,6 +1105,10 @@ int __init early_brk64(unsigned long addr, unsigned long esr, > #ifdef CONFIG_KASAN_SW_TAGS > if ((esr_comment(esr) & ~KASAN_BRK_MASK) == KASAN_BRK_IMM) > return kasan_handler(regs, esr) != DBG_HOOK_HANDLED; > +#endif > +#ifdef CONFIG_UBSAN_TRAP > + if ((esr_comment(esr) & ~UBSAN_BRK_MASK) == UBSAN_BRK_IMM) > + return ubsan_handler(regs, esr) != DBG_HOOK_HANDLED; > #endif > return bug_handler(regs, esr) != DBG_HOOK_HANDLED; > } > @@ -1104,6 +1122,9 @@ void __init trap_init(void) > register_kernel_break_hook(&fault_break_hook); > #ifdef CONFIG_KASAN_SW_TAGS > register_kernel_break_hook(&kasan_break_hook); > +#endif > +#ifdef CONFIG_UBSAN_TRAP > + register_kernel_break_hook(&ubsan_break_hook); > #endif > debug_traps_init(); > } > diff --git a/include/linux/ubsan.h b/include/linux/ubsan.h > new file mode 100644 > index 000000000000..bff7445498de > --- /dev/null > +++ b/include/linux/ubsan.h > @@ -0,0 +1,9 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > +#ifndef _LINUX_UBSAN_H > +#define _LINUX_UBSAN_H > + > +#ifdef CONFIG_UBSAN_TRAP > +const char *report_ubsan_failure(struct pt_regs *regs, u32 check_type); > +#endif > + > +#endif > diff --git a/lib/Makefile b/lib/Makefile > index 4d9461bfea42..81b988bf9448 100644 > --- a/lib/Makefile > +++ b/lib/Makefile > @@ -340,9 +340,7 @@ quiet_cmd_build_OID_registry = GEN $@ > clean-files += oid_registry_data.c > > obj-$(CONFIG_UCS2_STRING) += ucs2_string.o > -ifneq ($(CONFIG_UBSAN_TRAP),y) > obj-$(CONFIG_UBSAN) += ubsan.o > -endif > > UBSAN_SANITIZE_ubsan.o := n > KASAN_SANITIZE_ubsan.o := n > diff --git a/lib/ubsan.c b/lib/ubsan.c > index 60c7099857a0..98a671ec56e9 100644 > --- a/lib/ubsan.c > +++ b/lib/ubsan.c > @@ -18,6 +18,58 @@ > > #include "ubsan.h" > > +#ifdef CONFIG_UBSAN_TRAP > +const char *report_ubsan_failure(struct pt_regs *regs, u32 check_type) > +{ > + switch (check_type) { > + case ubsan_add_overflow: > + return "UBSAN: addition overflow"; It would be nice if we could avoid duplicating this UBSAN: prefix 21x times. > + case ubsan_builtin_unreachable: > + return "UBSAN: unreachable code"; > + case ubsan_cfi_check_fail: > + return "UBSAN: CFI failure"; > + case ubsan_divrem_overflow: > + return "UBSAN: divide/remainder overflow"; > + case ubsan_function_type_mismatch: > + return "UBSAN: function type mismatch"; > + case ubsan_implicit_conversion: > + return "UBSAN: implicit conversion"; > + case ubsan_invalid_builtin: > + return "UBSAN: invalid builtin"; > + case ubsan_invalid_objc_cast: > + return "UBSAN: invalid object cast"; > + case ubsan_load_invalid_value: > + return "UBSAN: loading invalid value"; > + case ubsan_missing_return: > + return "UBSAN: missing return"; > + case ubsan_mul_overflow: > + return "UBSAN: multiplication overflow"; > + case ubsan_negate_overflow: > + return "UBSAN: negation overflow"; > + case ubsan_nonnull_arg: > + return "UBSAN: non-NULL argument"; > + case ubsan_nonnull_return: > + return "UBSAN: non-NULL return"; > + case ubsan_out_of_bounds: > + return "UBSAN: array index out of bounds"; > + case ubsan_pointer_overflow: > + return "UBSAN: pointer overflow"; > + case ubsan_shift_out_of_bounds: > + return "UBSAN: shift out of bounds"; > + case ubsan_sub_overflow: > + return "UBSAN: subtraction overflow"; > + case ubsan_type_mismatch: > + return "UBSAN: type mismatch"; > + case ubsan_alignment_assumption: > + return "UBSAN: alignment assumption"; > + case ubsan_vla_bound_not_positive: > + return "UBSAN: VLA bounds not positive"; > + default: > + return "UBSAN: unknown failure"; > + } > +} > + > +#else > static const char * const type_check_kinds[] = { > "load of", > "store to", > @@ -384,3 +436,5 @@ void __ubsan_handle_alignment_assumption(void *_data, unsigned long ptr, > ubsan_epilogue(); > } > EXPORT_SYMBOL(__ubsan_handle_alignment_assumption); > + > +#endif /* !CONFIG_UBSAN_TRAP */ > diff --git a/lib/ubsan.h b/lib/ubsan.h > index 9a0b71c5ff9f..9c7f00f550f5 100644 > --- a/lib/ubsan.h > +++ b/lib/ubsan.h > @@ -2,6 +2,34 @@ > #ifndef _LIB_UBSAN_H > #define _LIB_UBSAN_H > > +enum ubsan_checks { > + ubsan_add_overflow, > + ubsan_builtin_unreachable, > + ubsan_cfi_check_fail, > + ubsan_divrem_overflow, > + ubsan_dynamic_type_cache_miss, > + ubsan_float_cast_overflow, > + ubsan_function_type_mismatch, > + ubsan_implicit_conversion, > + ubsan_invalid_builtin, > + ubsan_invalid_objc_cast, > + ubsan_load_invalid_value, > + ubsan_missing_return, > + ubsan_mul_overflow, > + ubsan_negate_overflow, > + ubsan_nullability_arg, > + ubsan_nullability_return, > + ubsan_nonnull_arg, > + ubsan_nonnull_return, > + ubsan_out_of_bounds, > + ubsan_pointer_overflow, > + ubsan_shift_out_of_bounds, > + ubsan_sub_overflow, > + ubsan_type_mismatch, > + ubsan_alignment_assumption, > + ubsan_vla_bound_not_positive, > +}; > + > enum { > type_kind_int = 0, > type_kind_float = 1, > -- > 2.34.1 >
On 2/3/2023 4:06 AM, Kees Cook wrote: > On arm64, Clang encodes the UBSAN check type in the esr. Extract this > and actually report UBSAN traps with some specificity when building with > CONFIG_UBSAN_TRAP. Before: > > Internal error: BRK handler: 00000000f20003e8 [#1] PREEMPT SMP > > After: > > Internal error: UBSAN: shift out of bounds: 00000000f2005514 [#1] PREEMPT SMP > > Cc: Catalin Marinas <catalin.marinas@arm.com> > Cc: Will Deacon <will@kernel.org> > Cc: Mark Rutland <mark.rutland@arm.com> > Cc: John Stultz <jstultz@google.com> > Cc: Yongqin Liu <yongqin.liu@linaro.org> > Cc: Sami Tolvanen <samitolvanen@google.com> > Cc: Ard Biesheuvel <ardb@kernel.org> > Cc: Yury Norov <yury.norov@gmail.com> > Cc: Andrey Konovalov <andreyknvl@gmail.com> > Cc: Marco Elver <elver@google.com> > Cc: linux-arm-kernel@lists.infradead.org > Cc: llvm@lists.linux.dev > Signed-off-by: Kees Cook <keescook@chromium.org> Thanks for handling this,,it will really help in decoding abstracted BRK handler errors to some extent. Acked-by: Mukesh Ojha <quic_mojha@quicinc.com> -Mukesh > --- > arch/arm64/include/asm/brk-imm.h | 2 ++ > arch/arm64/kernel/traps.c | 21 +++++++++++++ > include/linux/ubsan.h | 9 ++++++ > lib/Makefile | 2 -- > lib/ubsan.c | 54 ++++++++++++++++++++++++++++++++ > lib/ubsan.h | 28 +++++++++++++++++ > 6 files changed, 114 insertions(+), 2 deletions(-) > create mode 100644 include/linux/ubsan.h > > diff --git a/arch/arm64/include/asm/brk-imm.h b/arch/arm64/include/asm/brk-imm.h > index 6e000113e508..3f0f0d03268b 100644 > --- a/arch/arm64/include/asm/brk-imm.h > +++ b/arch/arm64/include/asm/brk-imm.h > @@ -28,6 +28,8 @@ > #define BUG_BRK_IMM 0x800 > #define KASAN_BRK_IMM 0x900 > #define KASAN_BRK_MASK 0x0ff > +#define UBSAN_BRK_IMM 0x5500 > +#define UBSAN_BRK_MASK 0x00ff > > #define CFI_BRK_IMM_TARGET GENMASK(4, 0) > #define CFI_BRK_IMM_TYPE GENMASK(9, 5) > diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c > index 4c0caa589e12..87f42eb1c950 100644 > --- a/arch/arm64/kernel/traps.c > +++ b/arch/arm64/kernel/traps.c > @@ -26,6 +26,7 @@ > #include <linux/syscalls.h> > #include <linux/mm_types.h> > #include <linux/kasan.h> > +#include <linux/ubsan.h> > #include <linux/cfi.h> > > #include <asm/atomic.h> > @@ -1074,6 +1075,19 @@ static struct break_hook kasan_break_hook = { > }; > #endif > > +#ifdef CONFIG_UBSAN_TRAP > +static int ubsan_handler(struct pt_regs *regs, unsigned long esr) > +{ > + die(report_ubsan_failure(regs, esr & UBSAN_BRK_MASK), regs, esr); > + return DBG_HOOK_HANDLED; > +} > + > +static struct break_hook ubsan_break_hook = { > + .fn = ubsan_handler, > + .imm = UBSAN_BRK_IMM, > + .mask = UBSAN_BRK_MASK, > +}; > +#endif > > #define esr_comment(esr) ((esr) & ESR_ELx_BRK64_ISS_COMMENT_MASK) > > @@ -1091,6 +1105,10 @@ int __init early_brk64(unsigned long addr, unsigned long esr, > #ifdef CONFIG_KASAN_SW_TAGS > if ((esr_comment(esr) & ~KASAN_BRK_MASK) == KASAN_BRK_IMM) > return kasan_handler(regs, esr) != DBG_HOOK_HANDLED; > +#endif > +#ifdef CONFIG_UBSAN_TRAP > + if ((esr_comment(esr) & ~UBSAN_BRK_MASK) == UBSAN_BRK_IMM) > + return ubsan_handler(regs, esr) != DBG_HOOK_HANDLED; > #endif > return bug_handler(regs, esr) != DBG_HOOK_HANDLED; > } > @@ -1104,6 +1122,9 @@ void __init trap_init(void) > register_kernel_break_hook(&fault_break_hook); > #ifdef CONFIG_KASAN_SW_TAGS > register_kernel_break_hook(&kasan_break_hook); > +#endif > +#ifdef CONFIG_UBSAN_TRAP > + register_kernel_break_hook(&ubsan_break_hook); > #endif > debug_traps_init(); > } > diff --git a/include/linux/ubsan.h b/include/linux/ubsan.h > new file mode 100644 > index 000000000000..bff7445498de > --- /dev/null > +++ b/include/linux/ubsan.h > @@ -0,0 +1,9 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > +#ifndef _LINUX_UBSAN_H > +#define _LINUX_UBSAN_H > + > +#ifdef CONFIG_UBSAN_TRAP > +const char *report_ubsan_failure(struct pt_regs *regs, u32 check_type); > +#endif > + > +#endif > diff --git a/lib/Makefile b/lib/Makefile > index 4d9461bfea42..81b988bf9448 100644 > --- a/lib/Makefile > +++ b/lib/Makefile > @@ -340,9 +340,7 @@ quiet_cmd_build_OID_registry = GEN $@ > clean-files += oid_registry_data.c > > obj-$(CONFIG_UCS2_STRING) += ucs2_string.o > -ifneq ($(CONFIG_UBSAN_TRAP),y) > obj-$(CONFIG_UBSAN) += ubsan.o > -endif > > UBSAN_SANITIZE_ubsan.o := n > KASAN_SANITIZE_ubsan.o := n > diff --git a/lib/ubsan.c b/lib/ubsan.c > index 60c7099857a0..98a671ec56e9 100644 > --- a/lib/ubsan.c > +++ b/lib/ubsan.c > @@ -18,6 +18,58 @@ > > #include "ubsan.h" > > +#ifdef CONFIG_UBSAN_TRAP > +const char *report_ubsan_failure(struct pt_regs *regs, u32 check_type) > +{ > + switch (check_type) { > + case ubsan_add_overflow: > + return "UBSAN: addition overflow"; > + case ubsan_builtin_unreachable: > + return "UBSAN: unreachable code"; > + case ubsan_cfi_check_fail: > + return "UBSAN: CFI failure"; > + case ubsan_divrem_overflow: > + return "UBSAN: divide/remainder overflow"; > + case ubsan_function_type_mismatch: > + return "UBSAN: function type mismatch"; > + case ubsan_implicit_conversion: > + return "UBSAN: implicit conversion"; > + case ubsan_invalid_builtin: > + return "UBSAN: invalid builtin"; > + case ubsan_invalid_objc_cast: > + return "UBSAN: invalid object cast"; > + case ubsan_load_invalid_value: > + return "UBSAN: loading invalid value"; > + case ubsan_missing_return: > + return "UBSAN: missing return"; > + case ubsan_mul_overflow: > + return "UBSAN: multiplication overflow"; > + case ubsan_negate_overflow: > + return "UBSAN: negation overflow"; > + case ubsan_nonnull_arg: > + return "UBSAN: non-NULL argument"; > + case ubsan_nonnull_return: > + return "UBSAN: non-NULL return"; > + case ubsan_out_of_bounds: > + return "UBSAN: array index out of bounds"; > + case ubsan_pointer_overflow: > + return "UBSAN: pointer overflow"; > + case ubsan_shift_out_of_bounds: > + return "UBSAN: shift out of bounds"; > + case ubsan_sub_overflow: > + return "UBSAN: subtraction overflow"; > + case ubsan_type_mismatch: > + return "UBSAN: type mismatch"; > + case ubsan_alignment_assumption: > + return "UBSAN: alignment assumption"; > + case ubsan_vla_bound_not_positive: > + return "UBSAN: VLA bounds not positive"; > + default: > + return "UBSAN: unknown failure"; > + } > +} > + > +#else > static const char * const type_check_kinds[] = { > "load of", > "store to", > @@ -384,3 +436,5 @@ void __ubsan_handle_alignment_assumption(void *_data, unsigned long ptr, > ubsan_epilogue(); > } > EXPORT_SYMBOL(__ubsan_handle_alignment_assumption); > + > +#endif /* !CONFIG_UBSAN_TRAP */ > diff --git a/lib/ubsan.h b/lib/ubsan.h > index 9a0b71c5ff9f..9c7f00f550f5 100644 > --- a/lib/ubsan.h > +++ b/lib/ubsan.h > @@ -2,6 +2,34 @@ > #ifndef _LIB_UBSAN_H > #define _LIB_UBSAN_H > > +enum ubsan_checks { > + ubsan_add_overflow, > + ubsan_builtin_unreachable, > + ubsan_cfi_check_fail, > + ubsan_divrem_overflow, > + ubsan_dynamic_type_cache_miss, > + ubsan_float_cast_overflow, > + ubsan_function_type_mismatch, > + ubsan_implicit_conversion, > + ubsan_invalid_builtin, > + ubsan_invalid_objc_cast, > + ubsan_load_invalid_value, > + ubsan_missing_return, > + ubsan_mul_overflow, > + ubsan_negate_overflow, > + ubsan_nullability_arg, > + ubsan_nullability_return, > + ubsan_nonnull_arg, > + ubsan_nonnull_return, > + ubsan_out_of_bounds, > + ubsan_pointer_overflow, > + ubsan_shift_out_of_bounds, > + ubsan_sub_overflow, > + ubsan_type_mismatch, > + ubsan_alignment_assumption, > + ubsan_vla_bound_not_positive, > +}; > + > enum { > type_kind_int = 0, > type_kind_float = 1,
On Fri, Feb 03, 2023 at 09:58:26AM +0000, Mark Rutland wrote: > On Thu, Feb 02, 2023 at 10:36:57PM +0000, Kees Cook wrote: > > On arm64, Clang encodes the UBSAN check type in the esr. Extract this > > and actually report UBSAN traps with some specificity when building with > > CONFIG_UBSAN_TRAP. Before: > > Really minor nit, but could we mention CONFIG_UBSAN_TRAP at the start, e.g. > change that first sentence to: > > | When CONFIG_UBSAN_TRAP=y on arm64, Clang encodes the UBSAN check type into a > | BRK immediate, which is reported in the ESR. > > I was initially confused since I was aware that there are usually direct > function calls for the reporting. Sure, I can rearrange the commit log. > > Other than that, this looks fine to me, and regardless of the above: > > Acked-by: Mark Rutland <mark.rutland@arm.com> Thanks! -Kees
On Fri, Feb 03, 2023 at 12:34:38PM +0100, Ard Biesheuvel wrote: > [...] > > + switch (check_type) { > > + case ubsan_add_overflow: > > + return "UBSAN: addition overflow"; > > It would be nice if we could avoid duplicating this UBSAN: prefix 21x times. Yeah, agreed. I didn't see a way around it without weirdness or loss of details. die() takes a string not a format string, so without really odd shenanigans (re-write a single string in memory?) this is the most straight forward. One idea, though, is to drop all the strings that'll never happen -- i.e. wrap individual case statements in the associated CONFIG_UBSAN_foo. I already dropped several strings that were never implemented in the kernel's UBSAN. I could be even more picky. I'll try this in v2...
diff --git a/arch/arm64/include/asm/brk-imm.h b/arch/arm64/include/asm/brk-imm.h index 6e000113e508..3f0f0d03268b 100644 --- a/arch/arm64/include/asm/brk-imm.h +++ b/arch/arm64/include/asm/brk-imm.h @@ -28,6 +28,8 @@ #define BUG_BRK_IMM 0x800 #define KASAN_BRK_IMM 0x900 #define KASAN_BRK_MASK 0x0ff +#define UBSAN_BRK_IMM 0x5500 +#define UBSAN_BRK_MASK 0x00ff #define CFI_BRK_IMM_TARGET GENMASK(4, 0) #define CFI_BRK_IMM_TYPE GENMASK(9, 5) diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c index 4c0caa589e12..87f42eb1c950 100644 --- a/arch/arm64/kernel/traps.c +++ b/arch/arm64/kernel/traps.c @@ -26,6 +26,7 @@ #include <linux/syscalls.h> #include <linux/mm_types.h> #include <linux/kasan.h> +#include <linux/ubsan.h> #include <linux/cfi.h> #include <asm/atomic.h> @@ -1074,6 +1075,19 @@ static struct break_hook kasan_break_hook = { }; #endif +#ifdef CONFIG_UBSAN_TRAP +static int ubsan_handler(struct pt_regs *regs, unsigned long esr) +{ + die(report_ubsan_failure(regs, esr & UBSAN_BRK_MASK), regs, esr); + return DBG_HOOK_HANDLED; +} + +static struct break_hook ubsan_break_hook = { + .fn = ubsan_handler, + .imm = UBSAN_BRK_IMM, + .mask = UBSAN_BRK_MASK, +}; +#endif #define esr_comment(esr) ((esr) & ESR_ELx_BRK64_ISS_COMMENT_MASK) @@ -1091,6 +1105,10 @@ int __init early_brk64(unsigned long addr, unsigned long esr, #ifdef CONFIG_KASAN_SW_TAGS if ((esr_comment(esr) & ~KASAN_BRK_MASK) == KASAN_BRK_IMM) return kasan_handler(regs, esr) != DBG_HOOK_HANDLED; +#endif +#ifdef CONFIG_UBSAN_TRAP + if ((esr_comment(esr) & ~UBSAN_BRK_MASK) == UBSAN_BRK_IMM) + return ubsan_handler(regs, esr) != DBG_HOOK_HANDLED; #endif return bug_handler(regs, esr) != DBG_HOOK_HANDLED; } @@ -1104,6 +1122,9 @@ void __init trap_init(void) register_kernel_break_hook(&fault_break_hook); #ifdef CONFIG_KASAN_SW_TAGS register_kernel_break_hook(&kasan_break_hook); +#endif +#ifdef CONFIG_UBSAN_TRAP + register_kernel_break_hook(&ubsan_break_hook); #endif debug_traps_init(); } diff --git a/include/linux/ubsan.h b/include/linux/ubsan.h new file mode 100644 index 000000000000..bff7445498de --- /dev/null +++ b/include/linux/ubsan.h @@ -0,0 +1,9 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _LINUX_UBSAN_H +#define _LINUX_UBSAN_H + +#ifdef CONFIG_UBSAN_TRAP +const char *report_ubsan_failure(struct pt_regs *regs, u32 check_type); +#endif + +#endif diff --git a/lib/Makefile b/lib/Makefile index 4d9461bfea42..81b988bf9448 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -340,9 +340,7 @@ quiet_cmd_build_OID_registry = GEN $@ clean-files += oid_registry_data.c obj-$(CONFIG_UCS2_STRING) += ucs2_string.o -ifneq ($(CONFIG_UBSAN_TRAP),y) obj-$(CONFIG_UBSAN) += ubsan.o -endif UBSAN_SANITIZE_ubsan.o := n KASAN_SANITIZE_ubsan.o := n diff --git a/lib/ubsan.c b/lib/ubsan.c index 60c7099857a0..98a671ec56e9 100644 --- a/lib/ubsan.c +++ b/lib/ubsan.c @@ -18,6 +18,58 @@ #include "ubsan.h" +#ifdef CONFIG_UBSAN_TRAP +const char *report_ubsan_failure(struct pt_regs *regs, u32 check_type) +{ + switch (check_type) { + case ubsan_add_overflow: + return "UBSAN: addition overflow"; + case ubsan_builtin_unreachable: + return "UBSAN: unreachable code"; + case ubsan_cfi_check_fail: + return "UBSAN: CFI failure"; + case ubsan_divrem_overflow: + return "UBSAN: divide/remainder overflow"; + case ubsan_function_type_mismatch: + return "UBSAN: function type mismatch"; + case ubsan_implicit_conversion: + return "UBSAN: implicit conversion"; + case ubsan_invalid_builtin: + return "UBSAN: invalid builtin"; + case ubsan_invalid_objc_cast: + return "UBSAN: invalid object cast"; + case ubsan_load_invalid_value: + return "UBSAN: loading invalid value"; + case ubsan_missing_return: + return "UBSAN: missing return"; + case ubsan_mul_overflow: + return "UBSAN: multiplication overflow"; + case ubsan_negate_overflow: + return "UBSAN: negation overflow"; + case ubsan_nonnull_arg: + return "UBSAN: non-NULL argument"; + case ubsan_nonnull_return: + return "UBSAN: non-NULL return"; + case ubsan_out_of_bounds: + return "UBSAN: array index out of bounds"; + case ubsan_pointer_overflow: + return "UBSAN: pointer overflow"; + case ubsan_shift_out_of_bounds: + return "UBSAN: shift out of bounds"; + case ubsan_sub_overflow: + return "UBSAN: subtraction overflow"; + case ubsan_type_mismatch: + return "UBSAN: type mismatch"; + case ubsan_alignment_assumption: + return "UBSAN: alignment assumption"; + case ubsan_vla_bound_not_positive: + return "UBSAN: VLA bounds not positive"; + default: + return "UBSAN: unknown failure"; + } +} + +#else static const char * const type_check_kinds[] = { "load of", "store to", @@ -384,3 +436,5 @@ void __ubsan_handle_alignment_assumption(void *_data, unsigned long ptr, ubsan_epilogue(); } EXPORT_SYMBOL(__ubsan_handle_alignment_assumption); + +#endif /* !CONFIG_UBSAN_TRAP */ diff --git a/lib/ubsan.h b/lib/ubsan.h index 9a0b71c5ff9f..9c7f00f550f5 100644 --- a/lib/ubsan.h +++ b/lib/ubsan.h @@ -2,6 +2,34 @@ #ifndef _LIB_UBSAN_H #define _LIB_UBSAN_H +enum ubsan_checks { + ubsan_add_overflow, + ubsan_builtin_unreachable, + ubsan_cfi_check_fail, + ubsan_divrem_overflow, + ubsan_dynamic_type_cache_miss, + ubsan_float_cast_overflow, + ubsan_function_type_mismatch, + ubsan_implicit_conversion, + ubsan_invalid_builtin, + ubsan_invalid_objc_cast, + ubsan_load_invalid_value, + ubsan_missing_return, + ubsan_mul_overflow, + ubsan_negate_overflow, + ubsan_nullability_arg, + ubsan_nullability_return, + ubsan_nonnull_arg, + ubsan_nonnull_return, + ubsan_out_of_bounds, + ubsan_pointer_overflow, + ubsan_shift_out_of_bounds, + ubsan_sub_overflow, + ubsan_type_mismatch, + ubsan_alignment_assumption, + ubsan_vla_bound_not_positive, +}; + enum { type_kind_int = 0, type_kind_float = 1,
On arm64, Clang encodes the UBSAN check type in the esr. Extract this and actually report UBSAN traps with some specificity when building with CONFIG_UBSAN_TRAP. Before: Internal error: BRK handler: 00000000f20003e8 [#1] PREEMPT SMP After: Internal error: UBSAN: shift out of bounds: 00000000f2005514 [#1] PREEMPT SMP Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: John Stultz <jstultz@google.com> Cc: Yongqin Liu <yongqin.liu@linaro.org> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Ard Biesheuvel <ardb@kernel.org> Cc: Yury Norov <yury.norov@gmail.com> Cc: Andrey Konovalov <andreyknvl@gmail.com> Cc: Marco Elver <elver@google.com> Cc: linux-arm-kernel@lists.infradead.org Cc: llvm@lists.linux.dev Signed-off-by: Kees Cook <keescook@chromium.org> --- arch/arm64/include/asm/brk-imm.h | 2 ++ arch/arm64/kernel/traps.c | 21 +++++++++++++ include/linux/ubsan.h | 9 ++++++ lib/Makefile | 2 -- lib/ubsan.c | 54 ++++++++++++++++++++++++++++++++ lib/ubsan.h | 28 +++++++++++++++++ 6 files changed, 114 insertions(+), 2 deletions(-) create mode 100644 include/linux/ubsan.h