[PATCH v16 14/25] mm: pagewalk: fix termination condition in walk_pte_range()

Steven Price
2019-12-06T13:54:31Z

If walk_pte_range() is called with a 'end' argument that is beyond the
last page of memory (e.g. ~0UL) then the comparison between 'addr' and
'end' will always fail and the loop will be infinite. Instead change the
comparison to >= while accounting for overflow.

Signed-off-by: Steven Price <steven.price@arm.com>
---
mm/pagewalk.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index 1b9a3ba24c51..88104ab00a97 100644
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -18,9 +18,9 @@ static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
err = ops->pte_entry(pte, addr, addr + PAGE_SIZE, walk);
if (err)
break;
- addr += PAGE_SIZE;
- if (addr == end)
+ if (addr >= end - PAGE_SIZE)
break;
+ addr += PAGE_SIZE;
pte++;
}

--
2.20.1