From e0bbf92682ad1df36ef43104a036469ac0ab3a4a Mon Sep 17 00:00:00 2001 From: Justin Stitt Date: Mon, 11 Sep 2023 17:52:44 +0000 Subject: um,ethertap: Replace deprecated strncpy() with strscpy() `strncpy` is deprecated for use on NUL-terminated destination strings [1]. `gate_buf` should always be NUL-terminated and does not require NUL-padding. It is used as a string arg inside an argv array given to `run_helper()`. Due to this, let's use `strscpy` as it guarantees NUL-terminated on the destination buffer preventing potential buffer overreads [2]. This exact invocation was changed from `strcpy` to `strncpy` in commit 7879b1d94badb ("um,ethertap: use strncpy") back in 2015. Let's continue hardening our `str*cpy` apis and use the newer and safer `strscpy`! 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 Cc: linux-hardening@vger.kernel.org Cc: Kees Cook Signed-off-by: Justin Stitt Reviewed-by: Kees Cook Link: https://lore.kernel.org/r/20230911-strncpy-arch-um-os-linux-drivers-ethertap_user-c-v1-1-d9e53f52ab32@google.com Signed-off-by: Kees Cook --- arch/um/os-Linux/drivers/ethertap_user.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch') diff --git a/arch/um/os-Linux/drivers/ethertap_user.c b/arch/um/os-Linux/drivers/ethertap_user.c index 9483021d86dd..3363851a4ae8 100644 --- a/arch/um/os-Linux/drivers/ethertap_user.c +++ b/arch/um/os-Linux/drivers/ethertap_user.c @@ -105,7 +105,7 @@ static int etap_tramp(char *dev, char *gate, int control_me, sprintf(data_fd_buf, "%d", data_remote); sprintf(version_buf, "%d", UML_NET_VERSION); if (gate != NULL) { - strncpy(gate_buf, gate, 15); + strscpy(gate_buf, gate, sizeof(gate_buf)); args = setup_args; } else args = nosetup_args; -- cgit v1.2.3