Commit 32280e83 authored by Justin Stitt's avatar Justin Stitt Committed by Richard Weinberger
Browse files

um: Refactor deprecated strncpy to memcpy 

Use `memcpy` since `console_buf` is not expected to be NUL-terminated
and it more accurately describes what is happening with the buffers
`console_buf` and `string` as per Kees' analysis [1].

Also mark char buffer as `__nonstring` as per Kees' suggestion [2].

This change now makes it more clear what this code does and that
`console_buf` is not expected to be NUL-terminated.

Link: https://lore.kernel.org/all/202308081708.D5ADC80F@keescook/ [1]
Link: https://github.com/KSPP/linux/issues/90 [2]
Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings


Cc: linux-hardening@vger.kernel.org
Suggested-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarJustin Stitt <justinstitt@google.com>
Signed-off-by: default avatarRichard Weinberger <richard@nod.at>
parent ab7ca2eb

arch/um/drivers/mconsole_kern.c

+2 −2
Original line number Diff line number Diff line
@@ -554,7 +554,7 @@ struct mconsole_output { 


static DEFINE_SPINLOCK(client_lock);

static LIST_HEAD(clients);

static char console_buf[MCONSOLE_MAX_DATA];

static char console_buf[MCONSOLE_MAX_DATA] __nonstring;



static void console_write(struct console *console, const char *string,

			  unsigned int len)
@@ -567,7 +567,7 @@ static void console_write(struct console *console, const char *string, 


	while (len > 0) {

		n = min((size_t) len, ARRAY_SIZE(console_buf));

		strncpy(console_buf, string, n);

		memcpy(console_buf, string, n);

		string += n;

		len -= n;