On Mon, Mar 18, 2024 at 11:02:12PM +0000, Justin Stitt wrote: > strncpy() is deprecated for use on NUL-terminated destination strings > [1] and as such we should prefer more robust and less ambiguous string > interfaces. > > We expect nc->if_name to be NUL-terminated based on existing manual > NUL-byte assignments and checks: > | nc.if_name[IFNAMSIZ-1] = '\0'; > ... > | if (nc->if_name[0] != '\0') > > Let's use the new 2-argument strscpy() since it guarantees > NUL-termination on the destination buffer while correctly using the > destination buffers size to bound the operation. We may need for -rc1 (or -rc2), depending on when subsystem tree re-open for landing patches to use the 2-arg versio, but, regardless, it looks right: Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx> -Kees > > Link: https://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 > Cc: linux-hardening@xxxxxxxxxxxxxxx > Signed-off-by: Justin Stitt <justinstitt@xxxxxxxxxx> > --- > Note: build-tested only. > > Found with: $ rg "strncpy\(" > --- > drivers/tty/n_gsm.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c > index 4036566febcb..f5b0d91d32a7 100644 > --- a/drivers/tty/n_gsm.c > +++ b/drivers/tty/n_gsm.c > @@ -4010,7 +4010,7 @@ static int gsm_create_network(struct gsm_dlci *dlci, struct gsm_netconfig *nc) > mux_net = netdev_priv(net); > mux_net->dlci = dlci; > kref_init(&mux_net->ref); > - strncpy(nc->if_name, net->name, IFNAMSIZ); /* return net name */ > + strscpy(nc->if_name, net->name); /* return net name */ > > /* reconfigure dlci for network */ > dlci->prev_adaption = dlci->adaption; > > --- > base-commit: bf3a69c6861ff4dc7892d895c87074af7bc1c400 > change-id: 20240318-strncpy-drivers-tty-n_gsm-c-ab1336e0e196 > > Best regards, > -- > Justin Stitt <justinstitt@xxxxxxxxxx> > > -- Kees Cook
