[37/67] mm: pagewalk: fix termination condition in walk_pte_range()

Commit Message

Andrew Morton Feb. 4, 2020, 1:35 a.m. UTC

From: Steven Price <[e-mail]>
Subject: mm: pagewalk: fix termination condition in walk_pte_range()

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.

Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Steven Price <[e-mail]>
Cc: Albert Ou <[e-mail]>
Cc: Alexandre Ghiti <[e-mail]>
Cc: Andy Lutomirski <[e-mail]>
Cc: Ard Biesheuvel <[e-mail]>
Cc: Arnd Bergmann <[e-mail]>
Cc: Benjamin Herrenschmidt <[e-mail]>
Cc: Borislav Petkov <[e-mail]>
Cc: Catalin Marinas <[e-mail]>
Cc: Christian Borntraeger <[e-mail]>
Cc: Dave Hansen <[e-mail]>
Cc: David S. Miller <[e-mail]>
Cc: Heiko Carstens <[e-mail]>
Cc: "H. Peter Anvin" <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: James Hogan <[e-mail]>
Cc: James Morse <[e-mail]>
Cc: Jerome Glisse <[e-mail]>
Cc: "Liang, Kan" <[e-mail]>
Cc: Mark Rutland <[e-mail]>
Cc: Michael Ellerman <[e-mail]>
Cc: Paul Burton <[e-mail]>
Cc: Paul Mackerras <[e-mail]>
Cc: Paul Walmsley <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Ralf Baechle <[e-mail]>
Cc: Russell King <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Cc: Vasily Gorbik <[e-mail]>
Cc: Vineet Gupta <[e-mail]>
Cc: Will Deacon <[e-mail]>
Cc: Zong Li <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 mm/pagewalk.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Patch

--- a/mm/pagewalk.c~mm-pagewalk-fix-termination-condition-in-walk_pte_range
+++ a/mm/pagewalk.c
@@ -14,9 +14,9 @@  static int walk_pte_range_inner(pte_t *p
 		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;