kernel/linux.git/lib/ubsan.c, branch v6.19.11

ubsan: Fix incorrect hand-side used in handle

2025-08-25T13:11:06+00:00

__ubsan_handle_divrem_overflow() incorrectly uses the RHS to report. It always reports the same log: division of -1 by -1. But it should report division of LHS by -1. Signed-off-by: Junhui Pei Fixes: c6d308534aef ("UBSAN: run-time undefined behavior sanity checker") Link: https://lore.kernel.org/r/20250602153841.62935-1-paradoxskin233@gmail.com Signed-off-by: Kees Cook

KVM: arm64: Introduce CONFIG_UBSAN_KVM_EL2

2025-05-07T10:21:35+00:00

Add a new Kconfig CONFIG_UBSAN_KVM_EL2 for KVM which enables UBSAN for EL2 code (in protected/nvhe/hvhe) modes. This will re-use the same checks enabled for the kernel for the hypervisor. The only difference is that for EL2 it always emits a "brk" instead of implementing hooks as the hypervisor can't print reports. The KVM code will re-use the same code for the kernel "report_ubsan_failure()" so #ifdefs are changed to also have this code for CONFIG_UBSAN_KVM_EL2 Signed-off-by: Mostafa Saleh Reviewed-by: Kees Cook Link: https://lore.kernel.org/r/20250430162713.1997569-4-smostafa@google.com Signed-off-by: Marc Zyngier

ubsan: Remove regs from report_ubsan_failure()

2025-05-07T10:21:35+00:00

report_ubsan_failure() doesn't use argument regs, and soon it will be called from the hypervisor context were regs are not available. So, remove the unused argument. Signed-off-by: Mostafa Saleh Acked-by: Kees Cook Link: https://lore.kernel.org/r/20250430162713.1997569-3-smostafa@google.com Signed-off-by: Marc Zyngier

ubsan/overflow: Rework integer overflow sanitizer option to turn on everything

2025-03-08T03:58:05+00:00

Since we're going to approach integer overflow mitigation a type at a time, we need to enable all of the associated sanitizers, and then opt into types one at a time. Rename the existing "signed wrap" sanitizer to just the entire topic area: "integer wrap". Enable the implicit integer truncation sanitizers, with required callbacks and tests. Notably, this requires features (currently) only available in Clang, so we can depend on the cc-option tests to determine availability instead of doing version tests. Link: https://lore.kernel.org/r/20250307041914.937329-1-kees@kernel.org Signed-off-by: Kees Cook

ubsan: Add awareness of signed integer overflow traps

2024-04-16T00:42:43+00:00

On arm64, UBSAN traps can be decoded from the trap instruction. Add the add, sub, and mul overflow trap codes now that CONFIG_UBSAN_SIGNED_WRAP exists. Seen under clang 19: Internal error: UBSAN: unrecognized failure code: 00000000f2005515 [#1] PREEMPT SMP Reported-by: Nathan Chancellor Closes: https://lore.kernel.org/lkml/20240411-fix-ubsan-in-hardening-config-v1-0-e0177c80ffaa@kernel.org Fixes: 557f8c582a9b ("ubsan: Reintroduce signed overflow sanitizer") Tested-by: Nathan Chancellor Link: https://lore.kernel.org/r/20240415182832.work.932-kees@kernel.org Signed-off-by: Kees Cook

ubsan: Reintroduce signed overflow sanitizer

2024-02-21T04:44:49+00:00

In order to mitigate unexpected signed wrap-around[1], bring back the signed integer overflow sanitizer. It was removed in commit 6aaa31aeb9cf ("ubsan: remove overflow checks") because it was effectively a no-op when combined with -fno-strict-overflow (which correctly changes signed overflow from being "undefined" to being explicitly "wrap around"). Compilers are adjusting their sanitizers to trap wrap-around and to detecting common code patterns that should not be instrumented (e.g. "var + offset < var"). Prepare for this and explicitly rename the option from "OVERFLOW" to "WRAP" to more accurately describe the behavior. To annotate intentional wrap-around arithmetic, the helpers wrapping_add/sub/mul_wrap() can be used for individual statements. At the function level, the __signed_wrap attribute can be used to mark an entire function as expecting its signed arithmetic to wrap around. For a single object file the Makefile can use "UBSAN_SIGNED_WRAP_target.o := n" to mark it as wrapping, and for an entire directory, "UBSAN_SIGNED_WRAP := n" can be used. Additionally keep these disabled under CONFIG_COMPILE_TEST for now. Link: https://github.com/KSPP/linux/issues/26 [1] Cc: Miguel Ojeda Cc: Nathan Chancellor Cc: Peter Zijlstra Cc: Hao Luo Reviewed-by: Marco Elver Reviewed-by: Justin Stitt Signed-off-by: Kees Cook

UBSAN: use the kernel panic message markers

2023-12-20T22:48:14+00:00

Use the same splat markers as panic does for easier matching by external tools scanning kernel dmesg for splats. Link: https://lkml.kernel.org/r/20231218135339.23209-1-bp@alien8.de Signed-off-by: Borislav Petkov (AMD) Cc: Andrey Ryabinin Signed-off-by: Andrew Morton

ubsan: add prototypes for internal functions

2023-05-30T23:42:01+00:00

Most of the functions in ubsan that are only called from generated code don't have a prototype, which W=1 builds warn about: lib/ubsan.c:226:6: error: no previous prototype for '__ubsan_handle_divrem_overflow' [-Werror=missing-prototypes] lib/ubsan.c:307:6: error: no previous prototype for '__ubsan_handle_type_mismatch' [-Werror=missing-prototypes] lib/ubsan.c:321:6: error: no previous prototype for '__ubsan_handle_type_mismatch_v1' [-Werror=missing-prototypes] lib/ubsan.c:335:6: error: no previous prototype for '__ubsan_handle_out_of_bounds' [-Werror=missing-prototypes] lib/ubsan.c:352:6: error: no previous prototype for '__ubsan_handle_shift_out_of_bounds' [-Werror=missing-prototypes] lib/ubsan.c:394:6: error: no previous prototype for '__ubsan_handle_builtin_unreachable' [-Werror=missing-prototypes] lib/ubsan.c:404:6: error: no previous prototype for '__ubsan_handle_load_invalid_value' [-Werror=missing-prototypes] Add prototypes for all of these to lib/ubsan.h, and remove the one that was already present in ubsan.c. Signed-off-by: Arnd Bergmann Reviewed-by: Fangrui Song Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20230517125102.930491-1-arnd@kernel.org

Merge tag 'hardening-v6.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

2023-02-21T19:07:23+00:00

Pull hardening updates from Kees Cook: "Beyond some specific LoadPin, UBSAN, and fortify features, there are other fixes scattered around in various subsystems where maintainers were okay with me carrying them in my tree or were non-responsive but the patches were reviewed by others: - Replace 0-length and 1-element arrays with flexible arrays in various subsystems (Paulo Miguel Almeida, Stephen Rothwell, Kees Cook) - randstruct: Disable Clang 15 support (Eric Biggers) - GCC plugins: Drop -std=gnu++11 flag (Sam James) - strpbrk(): Refactor to use strchr() (Andy Shevchenko) - LoadPin LSM: Allow root filesystem switching when non-enforcing - fortify: Use dynamic object size hints when available - ext4: Fix CFI function prototype mismatch - Nouveau: Fix DP buffer size arguments - hisilicon: Wipe entire crypto DMA pool on error - coda: Fully allocate sig_inputArgs - UBSAN: Improve arm64 trap code reporting - copy_struct_from_user(): Add minimum bounds check on kernel buffer size" * tag 'hardening-v6.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: randstruct: disable Clang 15 support uaccess: Add minimum bounds check on kernel buffer size arm64: Support Clang UBSAN trap codes for better reporting coda: Avoid partial allocation of sig_inputArgs gcc-plugins: drop -std=gnu++11 to fix GCC 13 build lib/string: Use strchr() in strpbrk() crypto: hisilicon: Wipe entire pool on error net/i40e: Replace 0-length array with flexible array io_uring: Replace 0-length array with flexible array ext4: Fix function prototype mismatch for ext4_feat_ktype i915/gvt: Replace one-element array with flexible-array member drm/nouveau/disp: Fix nvif_outp_acquire_dp() argument size LoadPin: Allow filesystem switch when not enforcing LoadPin: Move pin reporting cleanly out of locking LoadPin: Refactor sysctl initialization LoadPin: Refactor read-only check into a helper ARM: ixp4xx: Replace 0-length arrays with flexible arrays fortify: Use __builtin_dynamic_object_size() when available rxrpc: replace zero-lenth array with DECLARE_FLEX_ARRAY() helper

arm64: Support Clang UBSAN trap codes for better reporting

2023-02-08T23:26:58+00:00

When building with CONFIG_UBSAN_TRAP=y on arm64, Clang encodes the UBSAN check (handler) type in the esr. Extract this and actually report these traps as coming from the specific UBSAN check that tripped. Before: Internal error: BRK handler: 00000000f20003e8 [#1] PREEMPT SMP After: Internal error: UBSAN: shift out of bounds: 00000000f2005514 [#1] PREEMPT SMP Acked-by: Mark Rutland Reviewed-by: Ard Biesheuvel Acked-by: Mukesh Ojha Reviewed-by: Fangrui Song Cc: Catalin Marinas Cc: Will Deacon Cc: John Stultz Cc: Yongqin Liu Cc: Sami Tolvanen Cc: Yury Norov Cc: Andrey Konovalov Cc: Marco Elver Cc: linux-arm-kernel@lists.infradead.org Cc: llvm@lists.linux.dev Signed-off-by: Kees Cook