[v17,14/23] mm: pagewalk: fix termination condition in walk_pte_range()

Commit Message

Steven Price Dec. 18, 2019, 4:23 p.m. UTC

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 <[e-mail]>
---
 mm/pagewalk.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Patch

diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index 4b5ee92ba079..6732fc7ac4c8 100644
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -14,9 +14,9 @@  static int walk_pte_range_inner(pte_t *pte, unsigned long addr,
 		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++;
 	}
 	return err;