linux-kernel - [PATCH] x86/ioremap: Fix off-by-one in e820 check in memremap_should_map

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Message-ID: <20250418135955.58190-1-dmaluka@chromium.org>
Date: Fri, 18 Apr 2025 13:59:55 +0000
From: Dmytro Maluka <dmaluka@...omium.org>
To: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: Tom Lendacky <thomas.lendacky@....com>,
	Dmytro Maluka <dmaluka@...omium.org>,
	Andy Lutomirski <luto@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	x86@...nel.org (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)),
	"H. Peter Anvin" <hpa@...or.com>,
	linux-kernel@...r.kernel.org (open list:X86 MM)
Subject: [PATCH] x86/ioremap: Fix off-by-one in e820 check in memremap_should_map_decrypted()

The end address in e820__get_entry_type() is exclusive, not inclusive.

Note: untested, bug found by code inspection.

Signed-off-by: Dmytro Maluka <dmaluka@...omium.org>
---
 arch/x86/mm/ioremap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index 331e101bf801..a44800a6196e 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -578,7 +578,7 @@ static bool memremap_should_map_decrypted(resource_size_t phys_addr,
 	}
 
 	/* Check if the address is outside kernel usable area */
-	switch (e820__get_entry_type(phys_addr, phys_addr + size - 1)) {
+	switch (e820__get_entry_type(phys_addr, phys_addr + size)) {
 	case E820_TYPE_RESERVED:
 	case E820_TYPE_ACPI:
 	case E820_TYPE_NVS:
-- 
2.49.0.805.g082f7c87e0-goog