linux-hardening - [PATCH] lkdtm: cfi: Fix type width for masking PAC bits

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Date:   Tue, 26 Apr 2022 17:12:26 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Kees Cook <keescook@...omium.org>,
        kernel test robot <lkp@...el.com>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Arnd Bergmann <arnd@...db.de>,
        Dan Li <ashimida@...ux.alibaba.com>,
        linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: [PATCH] lkdtm: cfi: Fix type width for masking PAC bits

The masking for PAC bits wasn't handling 32-bit architectures correctly.
Replace the u64 cast with uintptr_t.

Reported-by: kernel test robot <lkp@...el.com>
Reported-by: Geert Uytterhoeven <geert@...ux-m68k.org>
Link: https://lore.kernel.org/lkml/CAMuHMdVz-J-1ZQ08u0bsQihDkcRmEPrtX5B_oRJ+Ns5jrasnUw@mail.gmail.com
Fixes: 2e53b877dc12 ("lkdtm: Add CFI_BACKWARD to test ROP mitigations")
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Arnd Bergmann <arnd@...db.de>
Signed-off-by: Kees Cook <keescook@...omium.org>
---
 drivers/misc/lkdtm/cfi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/misc/lkdtm/cfi.c b/drivers/misc/lkdtm/cfi.c
index 804965a480b7..666a7f4bc137 100644
--- a/drivers/misc/lkdtm/cfi.c
+++ b/drivers/misc/lkdtm/cfi.c
@@ -59,7 +59,7 @@ static void lkdtm_CFI_FORWARD_PROTO(void)
 #endif
 
 #define no_pac_addr(addr)      \
-	((__force __typeof__(addr))((__force u64)(addr) | PAGE_OFFSET))
+	((__force __typeof__(addr))((uintptr_t)(addr) | PAGE_OFFSET))
 
 /* The ultimate ROP gadget. */
 static noinline __no_ret_protection
-- 
2.32.0