lkml.org 
[lkml]   [2023]   [Sep]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
Subject[PATCH] xen/efi: refactor deprecated strncpy
From
`strncpy` is deprecated for use on NUL-terminated destination strings [1].

`efi_loader_signature` has space for 4 bytes. We are copying "Xen" (3 bytes)
plus a NUL-byte which makes 4 total bytes. With that being said, there is
currently not a bug with the current `strncpy()` implementation in terms of
buffer overreads but we should favor a more robust string interface
either way.

A suitable replacement is `strscpy` [2] due to the fact that it guarantees
NUL-termination on the destination buffer while being functionally the
same in this case.

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 <keescook@chromium.org>
Signed-off-by: Justin Stitt <justinstitt@google.com>
---
Note: build-tested
---
arch/x86/xen/efi.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/xen/efi.c b/arch/x86/xen/efi.c
index 863d0d6b3edc..7250d0e0e1a9 100644
--- a/arch/x86/xen/efi.c
+++ b/arch/x86/xen/efi.c
@@ -138,7 +138,7 @@ void __init xen_efi_init(struct boot_params *boot_params)
if (efi_systab_xen == NULL)
return;

- strncpy((char *)&boot_params->efi_info.efi_loader_signature, "Xen",
+ strscpy((char *)&boot_params->efi_info.efi_loader_signature, "Xen",
sizeof(boot_params->efi_info.efi_loader_signature));
boot_params->efi_info.efi_systab = (__u32)__pa(efi_systab_xen);
boot_params->efi_info.efi_systab_hi = (__u32)(__pa(efi_systab_xen) >> 32);
---
base-commit: 2dde18cd1d8fac735875f2e4987f11817cc0bc2c
change-id: 20230911-strncpy-arch-x86-xen-efi-c-14292f5a79ee
Best regards,
--
Justin Stitt <justinstitt@google.com>

\
 
 \ /
  Last update: 2023-09-12 00:01    [W:0.049 / U:0.404 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site