m68k: emu: Replace strlcpy() with strscpy()

strlcpy() reads the entire source buffer first.
This read may exceed the destination size limit.
This is both inefficient and can lead to linear read
overflows if a source string is not NUL-terminated [1].
In an effort to remove strlcpy() completely [2], replace
strlcpy() here with strscpy().

Direct replacement is safe here since return value of -errno
is used to check for truncation instead of sizeof(dest).

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
[2] https://github.com/KSPP/linux/issues/89

Signed-off-by: Azeem Shaikh <azeemshaikh38@gmail.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Link: https://lore.kernel.org/r/20230830185428.4109426-1-azeemshaikh38@gmail.com
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>

diff --git a/arch/m68k/emu/natfeat.c b/arch/m68k/emu/natfeat.c
index b19dc00026d9953b5353bbf25ba8bd8fdc33ccc9..d124c62022c2d10505c1cb7f79e1a38b703622dd 100644 (file)
--- a/arch/m68k/emu/natfeat.c
+++ b/arch/m68k/emu/natfeat.c
@@ -42,10 +42,10 @@ long nf_get_id(const char *feature_name)
 {
        /* feature_name may be in vmalloc()ed memory, so make a copy */
        char name_copy[32];
-       size_t n;
+       ssize_t n;
 
-       n = strlcpy(name_copy, feature_name, sizeof(name_copy));
-       if (n >= sizeof(name_copy))
+       n = strscpy(name_copy, feature_name, sizeof(name_copy));
+       if (n < 0)
                return 0;
 
        return nf_get_id_phys(virt_to_phys(name_copy));