Messages in this thread Patch in this message | | | Date | Thu, 31 Aug 2023 22:55:59 +0000 | Subject | [PATCH v3] arm64/sysreg: refactor deprecated strncpy | From | Justin Stitt <> |
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strncpy is deprecated [1] and should not be used if the src string is not NUL-terminated.
When dealing with `cmdline` we are counting the number of characters until a space then copying these over into `buf`. Let's not use any of the str*() functions since the src string is not necessarily NUL-terminated.
Prefer `memcpy()` alongside a forced NUL-termination as it more accurately describes what is going on within this function, i.e: copying from non NUL-terminated buffer into a NUL-terminated buffer.
Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1] Link: https://github.com/KSPP/linux/issues/90 Cc: linux-hardening@vger.kernel.org Suggested-by: Kees Cook <keescook@chromium.org> Signed-off-by: Justin Stitt <justinstitt@google.com> --- Here's a quick rundown on the history of this patch: 1) v1 (changes requested) 2) v2 (applied to arm64 (for-next/misc)) 3) v2 reverted (https://lore.kernel.org/all/20230831162227.2307863-1-smostafa@google.com/) 4) v3 (fixes problems with both v1 and v2)
Changes in v3: - Fix faulty logic and use memcpy over strscpy (thanks Mostafa and Kees) - Use '\0' instead of 0 to make it abundantly clear that `buf` is a NUL-terminated string - Link to v2: https://lore.kernel.org/r/20230811-strncpy-arch-arm64-v2-1-ba84eabffadb@google.com
Changes in v2: - Utilize return value from strscpy and check for truncation (thanks Kees) - Link to v1: https://lore.kernel.org/r/20230810-strncpy-arch-arm64-v1-1-f67f3685cd64@google.com --- arch/arm64/kernel/idreg-override.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/kernel/idreg-override.c b/arch/arm64/kernel/idreg-override.c index 2fe2491b692c..3addc09f8746 100644 --- a/arch/arm64/kernel/idreg-override.c +++ b/arch/arm64/kernel/idreg-override.c @@ -263,8 +263,8 @@ static __init void __parse_cmdline(const char *cmdline, bool parse_aliases) return; len = min(len, ARRAY_SIZE(buf) - 1); - strncpy(buf, cmdline, len); - buf[len] = 0; + memcpy(buf, cmdline, len); + buf[len] = '\0'; if (strcmp(buf, "--") == 0) return; --- base-commit: 706a741595047797872e669b3101429ab8d378ef change-id: 20230810-strncpy-arch-arm64-1f3d328bd9b8 Best regards, -- Justin Stitt <justinstitt@google.com>
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