linux-kernel - [tip: efi/urgent] efi: Allow EFI_MEMORY_XP and EFI_MEMORY

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Message-ID: <162176322031.29796.11878288049256642429.tip-bot2@tip-bot2>
Date:   Sun, 23 May 2021 09:47:00 -0000
From:   "tip-bot2 for Heiner Kallweit" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Heiner Kallweit <hkallweit1@...il.com>,
        Ard Biesheuvel <ardb@...nel.org>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: efi/urgent] efi: Allow EFI_MEMORY_XP and EFI_MEMORY_RO both to
 be cleared

The following commit has been merged into the efi/urgent branch of tip:

Commit-ID:     45add3cc99feaaf57d4b6f01d52d532c16a1caee
Gitweb:        https://git.kernel.org/tip/45add3cc99feaaf57d4b6f01d52d532c16a1caee
Author:        Heiner Kallweit <hkallweit1@...il.com>
AuthorDate:    Fri, 30 Apr 2021 16:22:51 +02:00
Committer:     Ard Biesheuvel <ardb@...nel.org>
CommitterDate: Sat, 22 May 2021 14:05:13 +02:00

efi: Allow EFI_MEMORY_XP and EFI_MEMORY_RO both to be cleared

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>
---
 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 5737cb0..0a9aba5 100644
--- a/drivers/firmware/efi/memattr.c
+++ b/drivers/firmware/efi/memattr.c
@@ -67,11 +67,6 @@ 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))) {