Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
From:   Peter Jones <pjones@redhat.com>
To:     Evgeniy Baskov <baskov@ispras.ru>
Cc:     Ard Biesheuvel <ardb@kernel.org>, Borislav Petkov <bp@alien8.de>,
        Andy Lutomirski <luto@kernel.org>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Ingo Molnar <mingo@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Alexey Khoroshilov <khoroshilov@ispras.ru>,
        Peter Jones <pjones@redhat.com>,
        Mario Limonciello <mario.limonciello@amd.com>,
        joeyli <jlee@suse.com>, lvc-project@linuxtesting.org,
        x86@kernel.org, linux-efi@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org
Subject: [PATCH 2/2] efi/x86: don't try to set page attributes on 0-sized regions.
Date:   Tue, 13 Dec 2022 13:04:03 -0500
Message-Id: <20221213180403.1308507-2-pjones@redhat.com>
In-Reply-To: <20221213180403.1308507-1-pjones@redhat.com>
References: <20221213180317.qoy2l3mcpjparocq@redhat.com>
 <20221213180403.1308507-1-pjones@redhat.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

In "efi/x86: Explicitly set sections memory attributes", the following
region is defined to help compute page permissions:

          /* .setup [image_base, _head] */
          efi_adjust_memory_range_protection(image_base,
                                             (unsigned long)_head - image_base,
                                             EFI_MEMORY_RO | EFI_MEMORY_XP);

In at least some cases, that will result in a size of 0, which will
produce an error and a message on the console, though no actual failure
will be caused in the boot process.

This patch checks that case in efi_adjust_memory_range_protection() and
returns the error without logging.

Signed-off-by: Peter Jones <pjones@redhat.com>
---
 drivers/firmware/efi/libstub/mem.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/firmware/efi/libstub/mem.c b/drivers/firmware/efi/libstub/mem.c
index d52841adcc2..d20b1986c9e 100644
--- a/drivers/firmware/efi/libstub/mem.c
+++ b/drivers/firmware/efi/libstub/mem.c
@@ -247,6 +247,9 @@ efi_status_t efi_adjust_memory_range_protection(unsigned long start,
 	efi_physical_addr_t rounded_start, rounded_end;
 	unsigned long attr_clear;
 
+	if (size == 0)
+		return EFI_INVALID_PARAMETER;
+
 	/*
 	 * This function should not be used to modify attributes
 	 * other than writable/executable.
-- 
2.38.1