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* [PATCH] lkdtm/fortify: Swap memcpy() for strncpy()
@ 2022-02-16 20:25 Kees Cook
  2022-02-18 10:02 ` Muhammad Usama Anjum
  0 siblings, 1 reply; 2+ messages in thread
From: Kees Cook @ 2022-02-16 20:25 UTC (permalink / raw)
  To: Muhammad Usama Anjum
  Cc: Kees Cook, Arnd Bergmann, Greg Kroah-Hartman, linux-kernel,
	linux-hardening

The memcpy() runtime defenses are still not landed, so test with
strncpy() for now.

Reported-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 drivers/misc/lkdtm/fortify.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/misc/lkdtm/fortify.c b/drivers/misc/lkdtm/fortify.c
index d06458a4858e..ab33bb5e2e7a 100644
--- a/drivers/misc/lkdtm/fortify.c
+++ b/drivers/misc/lkdtm/fortify.c
@@ -44,14 +44,14 @@ void lkdtm_FORTIFIED_SUBOBJECT(void)
 	strscpy(src, "over ten bytes", size);
 	size = strlen(src) + 1;
 
-	pr_info("trying to strcpy past the end of a member of a struct\n");
+	pr_info("trying to strncpy past the end of a member of a struct\n");
 
 	/*
-	 * memcpy(target.a, src, 20); will hit a compile error because the
+	 * strncpy(target.a, src, 20); will hit a compile error because the
 	 * compiler knows at build time that target.a < 20 bytes. Use a
 	 * volatile to force a runtime error.
 	 */
-	memcpy(target.a, src, size);
+	strncpy(target.a, src, size);
 
 	/* Store result to global to prevent the code from being eliminated */
 	fortify_scratch_space = target.a[3];
-- 
2.30.2


^ permalink raw reply related	[flat|nested] 2+ messages in thread

* Re: [PATCH] lkdtm/fortify: Swap memcpy() for strncpy()
  2022-02-16 20:25 [PATCH] lkdtm/fortify: Swap memcpy() for strncpy() Kees Cook
@ 2022-02-18 10:02 ` Muhammad Usama Anjum
  0 siblings, 0 replies; 2+ messages in thread
From: Muhammad Usama Anjum @ 2022-02-18 10:02 UTC (permalink / raw)
  To: Kees Cook
  Cc: usama.anjum, Arnd Bergmann, Greg Kroah-Hartman, linux-kernel,
	linux-hardening

On 2/17/22 1:25 AM, Kees Cook wrote:
> The memcpy() runtime defenses are still not landed, so test with
> strncpy() for now.
> 
> Reported-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Muhammad Usama Anjum <usama.anjum@collabora.com>

^ permalink raw reply	[flat|nested] 2+ messages in thread

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2022-02-16 20:25 [PATCH] lkdtm/fortify: Swap memcpy() for strncpy() Kees Cook
2022-02-18 10:02 ` Muhammad Usama Anjum

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