kallsyms: replace deprecated strncpy with strscpy

strncpy() is deprecated for use on NUL-terminated destination strings
[1] and as such we should prefer more robust and less ambiguous string
interfaces. The goal is to remove its use completely [2].

namebuf is eventually cleaned of any trailing llvm suffixes using
strstr(). This hints that namebuf should be NUL-terminated.

static void cleanup_symbol_name(char *s)
{
	char *res;
	...
	res = strstr(s, ".llvm.");
	...
}

Due to this, use strscpy() over strncpy() as it guarantees
NUL-termination on the destination buffer. Drop the -1 from the length
calculation as it is no longer needed to ensure NUL-termination.

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings
Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html
Link: https://github.com/KSPP/linux/issues/90
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Justin Stitt <justinstitt@google.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>

diff --git a/kernel/module/kallsyms.c b/kernel/module/kallsyms.c
index ef73ae7c89094bdad10f851489d98330bd40dc57..62fb57bb9f161cbbaa4a6310176318722bb54619 100644 (file)
--- a/kernel/module/kallsyms.c
+++ b/kernel/module/kallsyms.c
@@ -348,7 +348,7 @@ const char *module_address_lookup(unsigned long addr,
        }
        /* Make a copy in here where it's safe */
        if (ret) {
-               strncpy(namebuf, ret, KSYM_NAME_LEN - 1);
+               strscpy(namebuf, ret, KSYM_NAME_LEN);
                ret = namebuf;
        }
        preempt_enable();