dm log userspace: 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.

`lc` is already zero-allocated:
|       lc = kzalloc(sizeof(*lc), GFP_KERNEL);
... as such, any future NUL-padding is superfluous.

A suitable replacement is `strscpy` [2] due to the fact that it
guarantees NUL-termination on the destination buffer without
unnecessarily NUL-padding.

Let's also go with the more idiomatic `dest, src, sizeof(dest)` pattern
for destination buffers that the compiler can calculate the size for.

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
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Justin Stitt <justinstitt@google.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>

diff --git a/drivers/md/dm-log-userspace-base.c b/drivers/md/dm-log-userspace-base.c
index 5aace6ee6d4790fbccd8f8875c7dc69ec5159f85..7e4f27e86150d2f9f8bb188b39d09285ef55d123 100644 (file)
--- a/drivers/md/dm-log-userspace-base.c
+++ b/drivers/md/dm-log-userspace-base.c
@@ -224,7 +224,7 @@ static int userspace_ctr(struct dm_dirty_log *log, struct dm_target *ti,
 
        lc->usr_argc = argc;
 
-       strncpy(lc->uuid, argv[0], DM_UUID_LEN);
+       strscpy(lc->uuid, argv[0], sizeof(lc->uuid));
        argc--;
        argv++;
        spin_lock_init(&lc->flush_lock);