fortify: Short-circuit known-safe calls to strscpy()

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Replacing compile-time safe calls of strcpy()-related functions with
strscpy() was always calling the full strscpy() logic when a builtin
would be better. For example:

	char buf[16];
	strcpy(buf, "yes");

would reduce to __builtin_memcpy(buf, "yes", 4), but not if it was:

	strscpy(buf, yes, sizeof(buf));

Fix this by checking if all sizes are known at compile-time.

Cc: linux-hardening@vger.kernel.org
Tested-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>

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This commit is contained in:

Kees Cook 2022-10-02 09:17:03 -07:00

parent 41eefc46a3

commit 62e1cbfc5d

2 changed files with 23 additions and 0 deletions

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include/linux/fortify-string.h

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