From d232606773a0b09ec7f1ffc25f63abe801d011fd Mon Sep 17 00:00:00 2001 From: Justin Stitt Date: Fri, 11 Aug 2023 16:33:51 +0000 Subject: [PATCH] arm64/sysreg: refactor deprecated strncpy `strncpy` is deprecated for use on NUL-terminated destination strings [1]. Which seems to be the case here due to the forceful setting of `buf`'s tail to 0. A suitable replacement is `strscpy` [2] due to the fact that it guarantees NUL-termination on its destination buffer argument which is _not_ the case for `strncpy`! In this case, we can simplify the logic and also check for any silent truncation by using `strscpy`'s return value. This should have no functional change and yet uses a more robust and less ambiguous interface whilst reducing code complexity. Link: www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings[1] Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2] Link: https://github.com/KSPP/linux/issues/90 Suggested-by: Kees Cook Cc: linux-hardening@vger.kernel.org Signed-off-by: Justin Stitt Link: https://lore.kernel.org/r/20230811-strncpy-arch-arm64-v2-1-ba84eabffadb@google.com Signed-off-by: Will Deacon --- arch/arm64/kernel/idreg-override.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/arch/arm64/kernel/idreg-override.c b/arch/arm64/kernel/idreg-override.c index 2fe2491b692c..aee12c75b738 100644 --- a/arch/arm64/kernel/idreg-override.c +++ b/arch/arm64/kernel/idreg-override.c @@ -262,9 +262,9 @@ static __init void __parse_cmdline(const char *cmdline, bool parse_aliases) if (!len) return; - len = min(len, ARRAY_SIZE(buf) - 1); - strncpy(buf, cmdline, len); - buf[len] = 0; + len = strscpy(buf, cmdline, ARRAY_SIZE(buf)); + if (len == -E2BIG) + len = ARRAY_SIZE(buf) - 1; if (strcmp(buf, "--") == 0) return;