Tech Times reports:
Linux 7.2's merge window closed out a cleanup campaign on Friday that most kernel developers had stopped expecting to see end: the complete removal of strncpy(), a C string-copy function that the kernel's own documentation labels "actively dangerous," from every subsystem, driver, and architecture-specific file in the kernel source tree.
The merge landed June 20, 2026. After around 362 commits spread across six years of incremental work, no call site using the function remained, and the function itself — including the last per-CPU-architecture optimized implementations — was struck from the source. The removal matters beyond housekeeping. strncpy() is a persistent source of a specific class of memory error: kernel buffers that contain sensitive data can leak bytes past an unterminated string boundary, a pattern that enables memory disclosure vulnerabilities. Eliminating the function from the tree removes that entire class from the kernel's attack surface — and, critically, makes strncpy() unavailable to any future contributor, turning a best-practice suggestion into an enforced policy.
Phoronix notes it's replaced by five different functions:
In place of strncpy, Linux kernel code should use strscpy() for NUL terminated destinations, strscpy_pad() for NUl-terminated destinations with zero-padding, strtomem_pad() for non-NUL-terminated fixed-width fields, memcpy_and_pad() for bounded copies with explicit padding, or memcpy() for known-length memory copies.
"The reason five functions were needed," explains Tech Times, "is that different parts of the kernel were using strncpy() for five semantically distinct memory operations — each with a different intent, different termination requirement, and different padding behavior. "
The original function obscured all of those differences under a single ambiguous name. The 362-commit campaign to replace it was, in effect, a codebase-wide audit that forced every call site to declare its actual intent in code That is an engineering outcome with lasting value: the kernel's string-handling semantics are now explicit where they were previously implicit, and future maintainers can read a function name and understand what a copy operation actually does.
Linux 7.2's merge window closed out a cleanup campaign on Friday that most kernel developers had stopped expecting to see end: the complete removal of strncpy(), a C string-copy function that the kernel's own documentation labels "actively dangerous," from every subsystem, driver, and architecture-specific file in the kernel source tree.
The merge landed June 20, 2026. After around 362 commits spread across six years of incremental work, no call site using the function remained, and the function itself — including the last per-CPU-architecture optimized implementations — was struck from the source. The removal matters beyond housekeeping. strncpy() is a persistent source of a specific class of memory error: kernel buffers that contain sensitive data can leak bytes past an unterminated string boundary, a pattern that enables memory disclosure vulnerabilities. Eliminating the function from the tree removes that entire class from the kernel's attack surface — and, critically, makes strncpy() unavailable to any future contributor, turning a best-practice suggestion into an enforced policy.
Phoronix notes it's replaced by five different functions:
In place of strncpy, Linux kernel code should use strscpy() for NUL terminated destinations, strscpy_pad() for NUl-terminated destinations with zero-padding, strtomem_pad() for non-NUL-terminated fixed-width fields, memcpy_and_pad() for bounded copies with explicit padding, or memcpy() for known-length memory copies.
"The reason five functions were needed," explains Tech Times, "is that different parts of the kernel were using strncpy() for five semantically distinct memory operations — each with a different intent, different termination requirement, and different padding behavior. "
The original function obscured all of those differences under a single ambiguous name. The 362-commit campaign to replace it was, in effect, a codebase-wide audit that forced every call site to declare its actual intent in code That is an engineering outcome with lasting value: the kernel's string-handling semantics are now explicit where they were previously implicit, and future maintainers can read a function name and understand what a copy operation actually does.
Read more of this story at Slashdot.
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