linux-kernel - [PATCH v3 14/21] x86/kaslr: Make the type of number of slots/slot areas consistent

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Message-Id: <20200728225722.67457-15-nivedita@alum.mit.edu>
Date:   Tue, 28 Jul 2020 18:57:15 -0400
From:   Arvind Sankar <nivedita@...m.mit.edu>
To:     Kees Cook <keescook@...omium.org>, x86@...nel.org
Cc:     linux-kernel@...r.kernel.org
Subject: [PATCH v3 14/21] x86/kaslr: Make the type of number of slots/slot areas consistent

The number of slots can be unsigned int, since on 64-bit, the maximum
amount of memory is 2^52, the minimum alignment is 2^21, so the slot
number cannot be greater than 2^31. But in case future processors have
more than 52 physical address bits, make it unsigned long.

The slot areas are limited by MAX_SLOT_AREA, currently 100. It is
indexed by an int, but the number of areas is stored as unsigned long.
Change both to unsigned int for consistency.

Signed-off-by: Arvind Sankar <nivedita@...m.mit.edu>
---
 arch/x86/boot/compressed/kaslr.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
index 7c69fc10a782..a87800aa6eda 100644
--- a/arch/x86/boot/compressed/kaslr.c
+++ b/arch/x86/boot/compressed/kaslr.c
@@ -508,17 +508,15 @@ static bool mem_avoid_overlap(struct mem_vector *img,
 
 struct slot_area {
 	unsigned long addr;
-	int num;
+	unsigned long num;
 };
 
 #define MAX_SLOT_AREA 100
 
 static struct slot_area slot_areas[MAX_SLOT_AREA];
-
+static unsigned int slot_area_index;
 static unsigned long slot_max;
 
-static unsigned long slot_area_index;
-
 static void store_slot_info(struct mem_vector *region, unsigned long image_size)
 {
 	struct slot_area slot_area;
@@ -587,7 +585,7 @@ process_gb_huge_pages(struct mem_vector *region, unsigned long image_size)
 static unsigned long slots_fetch_random(void)
 {
 	unsigned long slot;
-	int i;
+	unsigned int i;
 
 	/* Handle case of no slots stored. */
 	if (slot_max == 0)
-- 
2.26.2