linux-kernel - [PATCH 4.9 02/29] efi: Allow EFI_MEMORY_XP and EFI_MEMORY

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Message-Id: <20210608175927.901577449@linuxfoundation.org>
Date:   Tue,  8 Jun 2021 20:26:56 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Heiner Kallweit <hkallweit1@...il.com>,
        Ard Biesheuvel <ardb@...nel.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.9 02/29] efi: Allow EFI_MEMORY_XP and EFI_MEMORY_RO both to be cleared

From: Heiner Kallweit <hkallweit1@...il.com>

[ Upstream commit 45add3cc99feaaf57d4b6f01d52d532c16a1caee ]

UEFI spec 2.9, p.108, table 4-1 lists the scenario that both attributes
are cleared with the description "No memory access protection is
possible for Entry". So we can have valid entries where both attributes
are cleared, so remove the check.

Signed-off-by: Heiner Kallweit <hkallweit1@...il.com>
Fixes: 10f0d2f577053 ("efi: Implement generic support for the Memory Attributes table")
Signed-off-by: Ard Biesheuvel <ardb@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/firmware/efi/memattr.c | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/drivers/firmware/efi/memattr.c b/drivers/firmware/efi/memattr.c
index 9faa09e7c31f..c2b991b9fa9e 100644
--- a/drivers/firmware/efi/memattr.c
+++ b/drivers/firmware/efi/memattr.c
@@ -68,11 +68,6 @@ static bool entry_is_valid(const efi_memory_desc_t *in, efi_memory_desc_t *out)
 		return false;
 	}
 
-	if (!(in->attribute & (EFI_MEMORY_RO | EFI_MEMORY_XP))) {
-		pr_warn("Entry attributes invalid: RO and XP bits both cleared\n");
-		return false;
-	}
-
 	if (PAGE_SIZE > EFI_PAGE_SIZE &&
 	    (!PAGE_ALIGNED(in->phys_addr) ||
 	     !PAGE_ALIGNED(in->num_pages << EFI_PAGE_SHIFT))) {
-- 
2.30.2