[PATCH 1/4] highmem: Enhance is_kmap_addr() to check kmap_local_page() mappings

[ira . weiny]

From: Ira Weiny <ira.weiny@xxxxxxxxx>

is_kmap_addr() is only looking at the kmap() address range which may
cause check_heap_object() to miss checking an overflow on a
kmap_local_page() page.

Add a check for the kmap_local_page() address range to is_kmap_addr().

Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: "Fabio M. De Francesco" <fmdefrancesco@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ira Weiny <ira.weiny@xxxxxxxxx>
---
 include/linux/highmem-internal.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/include/linux/highmem-internal.h b/include/linux/highmem-internal.h
index 034b1106d022..5fd5cb58f109 100644
--- a/include/linux/highmem-internal.h
+++ b/include/linux/highmem-internal.h
@@ -152,7 +152,10 @@ static inline void totalhigh_pages_add(long count)
 static inline bool is_kmap_addr(const void *x)
 {
 	unsigned long addr = (unsigned long)x;
-	return addr >= PKMAP_ADDR(0) && addr < PKMAP_ADDR(LAST_PKMAP);
+
+	return (addr >= PKMAP_ADDR(0) && addr < PKMAP_ADDR(LAST_PKMAP)) ||
+		(addr >= __fix_to_virt(FIX_KMAP_END) &&
+		 addr < __fix_to_virt(FIX_KMAP_BEGIN));
 }
 #else /* CONFIG_HIGHMEM */
 
-- 
2.37.2