linux-kernel - [PATCH v4] x86/ioremap: Use is_ioremap

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Message-ID: <20240824220111.84441-1-max8rr8@gmail.com>
Date: Sun, 25 Aug 2024 01:01:11 +0300
From: Max Ramanouski <max8rr8@...il.com>
To: x86@...nel.org,
	dave.hansen@...ux.intel.com,
	luto@...nel.org,
	peterz@...radead.org,
	linux-kernel@...r.kernel.org,
	linux-mm@...ck.org,
	tglx@...utronix.de,
	hch@...radead.org,
	apopple@...dia.com
Cc: Max Ramanouski <max8rr8@...il.com>,
	Christoph Hellwig <hch@....de>
Subject: [PATCH v4] x86/ioremap: Use is_ioremap_addr() in iounmap()

Restrict iounmap() to memory allocated in ioremap region, by using
is_ioremap_addr(). Similarly to the generic iounmap() implementation.

Additionally, add warning in case there is an attempt to iounmap()
invalid memory, instead of silently exiting, thus helping to
avoid incorrect usage of iounmap().

Due to VMALLOC_START on i386 not being present in asm/pgtable.h,
include for asm/vmalloc.h had to be added to include/linux/ioremap.h.

Reviewed-by: Christoph Hellwig <hch@....de>
Reviewed-by: Alistair Popple <apopple@...dia.com>
Signed-off-by: Max Ramanouski <max8rr8@...il.com>
---
 arch/x86/mm/ioremap.c   | 3 ++-
 include/linux/ioremap.h | 1 +
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index aa7d279321ea..70b02fc61d93 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -11,6 +11,7 @@
 #include <linux/init.h>
 #include <linux/io.h>
 #include <linux/ioport.h>
+#include <linux/ioremap.h>
 #include <linux/slab.h>
 #include <linux/vmalloc.h>
 #include <linux/mmiotrace.h>
@@ -457,7 +458,7 @@ void iounmap(volatile void __iomem *addr)
 {
 	struct vm_struct *p, *o;
 
-	if ((void __force *)addr <= high_memory)
+	if (WARN_ON_ONCE(!is_ioremap_addr((void __force *)addr)))
 		return;
 
 	/*
diff --git a/include/linux/ioremap.h b/include/linux/ioremap.h
index f0e99fc7dd8b..2bd1661fe9ad 100644
--- a/include/linux/ioremap.h
+++ b/include/linux/ioremap.h
@@ -4,6 +4,7 @@
 
 #include <linux/kasan.h>
 #include <asm/pgtable.h>
+#include <asm/vmalloc.h>
 
 #if defined(CONFIG_HAS_IOMEM) || defined(CONFIG_GENERIC_IOREMAP)
 /*
-- 
2.45.2