linux-kernel - [PATCH 3/3] efi/memattr: Include EFI memmap size in corruption warnings

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Message-Id: <20250106-efi_fw_bug-v1-3-01a8eb40bfeb@debian.org>
Date: Mon, 06 Jan 2025 11:02:52 -0800
From: Breno Leitao <leitao@...ian.org>
To: Ard Biesheuvel <ardb@...nel.org>
Cc: Gregory Price <gourry@...rry.net>, Usama Arif <usamaarif642@...il.com>, 
 linux-efi@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Breno Leitao <leitao@...ian.org>, kernel-team@...a.com
Subject: [PATCH 3/3] efi/memattr: Include EFI memmap size in corruption
 warnings

Add EFI memory map size to warning messages when a corrupted Memory
Attributes Table is detected, making it easier to diagnose firmware issues.

Signed-off-by: Breno Leitao <leitao@...ian.org>
---
 drivers/firmware/efi/memattr.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/firmware/efi/memattr.c b/drivers/firmware/efi/memattr.c
index 5f83cdea88b05cb325e9f90c14a0048131e53cfa..2c276bcc0df48352bec6cd96b69edf67a16f6069 100644
--- a/drivers/firmware/efi/memattr.c
+++ b/drivers/firmware/efi/memattr.c
@@ -22,7 +22,7 @@ unsigned long __ro_after_init efi_mem_attr_table = EFI_INVALID_TABLE_ADDR;
 void __init efi_memattr_init(void)
 {
 	efi_memory_attributes_table_t *tbl;
-	unsigned long size;
+	unsigned long size, efi_map_size;
 
 	if (efi_mem_attr_table == EFI_INVALID_TABLE_ADDR)
 		return;
@@ -49,9 +49,10 @@ void __init efi_memattr_init(void)
 	 * just be ignored altogether.
 	 */
 	size = tbl->num_entries * tbl->desc_size;
-	if (size > 3 * efi.memmap.nr_map * efi.memmap.desc_size) {
-		pr_warn(FW_BUG "Corrupted EFI Memory Attributes Table detected! (version == %u, desc_size == %u, num_entries == %u)\n",
-			tbl->version, tbl->desc_size, tbl->num_entries);
+	efi_map_size = efi.memmap.nr_map * efi.memmap.desc_size;
+	if (size > 3 * efi_map_size) {
+		pr_warn(FW_BUG "Corrupted EFI Memory Attributes Table detected! (version == %u, desc_size == %u, num_entries == %u, efi_map_size == %lu)\n",
+			tbl->version, tbl->desc_size, tbl->num_entries, efi_map_size);
 		goto unmap;
 	}
 

-- 
2.43.5