[v16,14/25] mm: pagewalk: fix termination condition in walk_pte_range()
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Message ID 20191206135316.47703-15-steven.price@arm.com
State New
Headers show
Series
  • Generic page walk and ptdump
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Commit Message

Steven Price Dec. 6, 2019, 1:53 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 <steven.price@arm.com>
---
 mm/pagewalk.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Patch
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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++;
 	}