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Subject[PATCH] arm64/mm: fix virtual address boundary check
Date
From: Miles Chen <miles.chen@mediatek.com>

The MODULES_VADDR is not the lowest possible
kernel virtual address. TASK_SIZE_64 may be larger than
MODULES_VADDR, FIXADDR_TOP, and PCI_IO_START.

Fix this by comparing TASK_SIZE_64 (highest user virtual address)
with VA_START (lowest kernel virtual address).

#define VA_BITS (CONFIG_ARM64_VA_BITS)
#define VA_START (UL(0xffffffffffffffff) << VA_BITS)
#define PAGE_OFFSET (UL(0xffffffffffffffff) << (VA_BITS - 1))
#define MODULES_END (PAGE_OFFSET)
#define MODULES_VADDR (MODULES_END - SZ_64M)
#define PCI_IO_END (MODULES_VADDR - SZ_2M)
#define PCI_IO_START (PCI_IO_END - PCI_IO_SIZE)
#define FIXADDR_TOP (PCI_IO_START - SZ_2M)
#define TASK_SIZE_64 (UL(1) << VA_BITS)

Signed-off-by: Miles Chen <miles.chen@mediatek.com>
---
arch/arm64/mm/init.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index f3b061e..7d75697 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -343,8 +343,8 @@ void __init mem_init(void)
#ifdef CONFIG_COMPAT
BUILD_BUG_ON(TASK_SIZE_32 > TASK_SIZE_64);
#endif
- BUILD_BUG_ON(TASK_SIZE_64 > MODULES_VADDR);
- BUG_ON(TASK_SIZE_64 > MODULES_VADDR);
+ BUILD_BUG_ON(TASK_SIZE_64 > VA_START);
+ BUG_ON(TASK_SIZE_64 > VA_START);

if (PAGE_SIZE >= 16384 && get_num_physpages() <= 128) {
extern int sysctl_overcommit_memory;
--
1.9.1
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