lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-Id: <20171025101419.26369-3-ard.biesheuvel@linaro.org>
Date:   Wed, 25 Oct 2017 11:14:19 +0100
From:   Ard Biesheuvel <ard.biesheuvel@...aro.org>
To:     linux-efi@...r.kernel.org, Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        "H . Peter Anvin" <hpa@...or.com>
Cc:     Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        linux-kernel@...r.kernel.org,
        Matt Fleming <matt@...eblueprint.co.uk>
Subject: [PATCH 2/2] arm64: efi: ignore EFI_MEMORY_XP attribute if RP and/or WP are set

The UEFI memory map is a bit vague about how to interpret the
EFI_MEMORY_XP attribute when it is combined with EFI_MEMORY_RP and/or
EFI_MEMORY_WP, which have retroactively been redefined as cacheability
attributes rather than permission attributes.

So let's ignore EFI_MEMORY_XP if _RP and/or _WP are also set. In this
case, it is likely that they are being used to describe the capability
of the region (i.e., whether it has the controls to reconfigure it as
non-executable) rather than the nature of the contents of the region
(i.e., whether it contains data that we will never attempt to execute)

Reported-by: Stephen Boyd <sboyd@...eaurora.org>
Tested-by: Stephen Boyd <sboyd@...eaurora.org>
Cc: Matt Fleming <matt@...eblueprint.co.uk>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
---
 arch/arm64/kernel/efi.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c
index 82cd07592519..f85ac58d08a3 100644
--- a/arch/arm64/kernel/efi.c
+++ b/arch/arm64/kernel/efi.c
@@ -48,7 +48,9 @@ static __init pteval_t create_mapping_protection(efi_memory_desc_t *md)
 		return pgprot_val(PAGE_KERNEL_ROX);
 
 	/* RW- */
-	if (attr & EFI_MEMORY_XP || type != EFI_RUNTIME_SERVICES_CODE)
+	if (((attr & (EFI_MEMORY_RP | EFI_MEMORY_WP | EFI_MEMORY_XP)) ==
+	     EFI_MEMORY_XP) ||
+	    type != EFI_RUNTIME_SERVICES_CODE)
 		return pgprot_val(PAGE_KERNEL);
 
 	/* RWX */
-- 
2.11.0

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ