kernel/linux.git/drivers/misc/lkdtm, branch v7.2-rc1

string: Remove strncpy() from the kernel

2026-06-18T23:39:31+00:00

strncpy() has been a persistent source of bugs due to its ambiguous intended usage and frequently counter-intuitive semantics: it may not NUL-terminate the destination, and it unconditionally zero-pads to the full length, which isn't always needed. All former callers have been migrated[1] to: - strscpy() for NUL-terminated destinations - strscpy_pad() for NUL-terminated destinations needing zero-padding - strtomem_pad() for non-NUL-terminated fixed-width fields - memcpy_and_pad() for bounded copies with explicit padding - memcpy() for known-length copies Remove the generic implementation, its declaration, the FORTIFY_SOURCE wrapper, and associated tests. Link: https://github.com/KSPP/linux/issues/90 [1] Signed-off-by: Kees Cook

lkdtm/powerpc: add PPC_RADIX_TLBIEL test for radix MCE validation

2026-05-21T10:21:01+00:00

Add a new LKDTM trigger (PPC_RADIX_TLBIEL) that executes a process-scoped radix TLBIEL instruction to exercise the radix MMU behaviour and associated machine check exception (MCE) handling paths. This provides a way to validate MCE handling in radix mode. Currently, there is no dedicated LKDTM test that exercises this path or allows triggering radix-specific machine check behaviour for validation. The test is only enabled on ppc64 systems with radix MMU support and If radix is not active, the trigger is skipped and reported as XFAIL. Co-developed-by: Ritesh Harjani (IBM) Signed-off-by: Ritesh Harjani (IBM) Signed-off-by: Sayali Patil Reviewed-by: Ritesh Harjani (IBM) Reviewed-by: Michael Ellerman Link: https://patch.msgid.link/85c9b59217bcecb3c7af52e9d5b175266771d7de.1778975974.git.sayalip@linux.ibm.com Signed-off-by: Kees Cook

lkdtm/powerpc: add isync after slbmte to enforce SLB update ordering

2026-05-21T10:21:00+00:00

The slbmte instruction modifies the Segment Lookaside Buffer, but without a context synchronizing operation the CPU is not guaranteed to observe the updated SLB state for subsequent instructions. This can result in use of stale translation state when memory is accessed immediately after SLB modifications. Add isync after each slbmte in the PPC_SLB_MULTIHIT test to ensure proper ordering of SLB updates before subsequent memory accesses. This aligns with Power ISA context synchronization requirements for changes in address translation state and improves the reliability of SLB multihit injection tests in hash MMU mode. Suggested-by: Ritesh Harjani (IBM) Signed-off-by: Sayali Patil Reviewed-by: Ritesh Harjani (IBM) Reviewed-by: Michael Ellerman Link: https://patch.msgid.link/2f8d430962a96a7498903b994f081deee4a4d97a.1778975974.git.sayalip@linux.ibm.com Signed-off-by: Kees Cook

lkdtm: Add case to provoke a crash in EFI runtime services

2026-05-21T10:19:47+00:00

Add a lkdtm test case that triggers a fault during the execution of a EFI runtime service by passing a read-only variable as a by-ref argument that the firmware is supposed to update. This is useful for testing the graceful handling of faults/exception in EFI platform firmware, which is implemented on x86 and arm64. Signed-off-by: Ard Biesheuvel Link: https://patch.msgid.link/20260501170156.2833364-2-ardb+git@google.com Signed-off-by: Kees Cook

lkdtm/fortify: Drop unneeded FORTIFY_STR_OBJECT test

2026-03-31T23:53:47+00:00

The str* family of fortified functions all use member-sized limits for a while now, so the FORTIFY_STR_OBJECT test is redundant to FORTIFY_STR_MEMBER. While here, replace the strncpy() use with strscpy(), as strncpy() is being removed. Link: https://patch.msgid.link/20260324020726.work.624-kees@kernel.org Signed-off-by: Kees Cook

Convert 'alloc_flex' family to use the new default GFP_KERNEL argument

2026-02-22T01:09:51+00:00

This is the exact same thing as the 'alloc_obj()' version, only much smaller because there are a lot fewer users of the *alloc_flex() interface. As with alloc_obj() version, this was done entirely with mindless brute force, using the same script, except using 'flex' in the pattern rather than 'objs*'. Signed-off-by: Linus Torvalds

Convert 'alloc_obj' family to use the new default GFP_KERNEL argument

2026-02-22T01:09:51+00:00

This was done entirely with mindless brute force, using git grep -l '\

treewide: Replace kmalloc with kmalloc_obj for non-scalar types

2026-02-21T09:02:28+00:00

This is the result of running the Coccinelle script from scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to avoid scalar types (which need careful case-by-case checking), and instead replace kmalloc-family calls that allocate struct or union object instances: Single allocations: kmalloc(sizeof(TYPE), ...) are replaced with: kmalloc_obj(TYPE, ...) Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...) are replaced with: kmalloc_objs(TYPE, COUNT, ...) Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...) are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...) (where TYPE may also be *VAR) The resulting allocations no longer return "void *", instead returning "TYPE *". Signed-off-by: Kees Cook

lkdtm/bugs: Add __counted_by_ptr() test PTR_BOUNDS

2026-01-17T19:00:37+00:00

Provide run-time validation of the __counted_by_ptr() annotation via newly added PTR_BOUNDS LKDTM test. Link: https://patch.msgid.link/20251020220118.1226740-2-kees@kernel.org Signed-off-by: Kees Cook

lkdtm/bugs: Do not confuse the clang/objtool with busy wait loop

2025-12-19T15:09:09+00:00

Since commit eb972eab0794 ("lkdtm/bugs: Add cases for BUG and PANIC occurring in hardirq context"), building with clang for x86_64 results in the following warnings: vmlinux.o: warning: objtool: lkdtm_PANIC_IN_HARDIRQ(): unexpected end of section .text.lkdtm_PANIC_IN_HARDIRQ vmlinux.o: warning: objtool: lkdtm_BUG_IN_HARDIRQ(): unexpected end of section .text.lkdtm_BUG_IN_HARDIRQ caused by busy "while (wait_for_...);" loops. Add READ_ONCE() and cpu_relax() to better indicate the intention and avoid any unwanted compiler optimisations. Fixes: eb972eab0794 ("lkdtm/bugs: Add cases for BUG and PANIC occurring in hardirq context") Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202512190111.jxFSqxUH-lkp@intel.com/ Signed-off-by: Catalin Marinas