string: Remove strncpy() from the kernel

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.

Kees Cook committed 7 months ago

Commit 079a0281 parent 58c4ce88 files · +28 −160Browse files

Showing the changes to lib/string.c (1 of 8 files). Show all

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lib/string.c+0−16

@@ -88,22 +88,6 @@ char strcpy(char dest, const char *src) · 87 unmodified lines
88	88	EXPORT_SYMBOL(strcpy);
89	89	#endif
90	90
91		−#ifndef __HAVE_ARCH_STRNCPY
92		−char strncpy(char dest, const char *src, size_t count)
93		−{
94		− char *tmp = dest;
95		−
96		− while (count) {
97		− if ((tmp = src) != 0)
98		− src++;
99		− tmp++;
100		− count--;
101		− }
102		− return dest;
103		−}
104		−EXPORT_SYMBOL(strncpy);
105		−#endif
106		−
107	91	#ifdef __BIG_ENDIAN
108	92	# define ALLBUTLAST_BYTE_MASK (~255ul)
109	93	#else