From 556637cdabcd5918c7d4a1a2679b8f86fc81e891 Mon Sep 17 00:00:00 2001 From: Johannes Weiner Date: Mon, 28 Apr 2008 02:11:47 -0700 Subject: [PATCH] mm: fix possible off-by-one in walk_pte_range() After the loop in walk_pte_range() pte might point to the first address after the pmd it walks. The pte_unmap() is then applied to something bad. Spotted by Roel Kluin and Andreas Schwab. Signed-off-by: Johannes Weiner Cc: Roel Kluin <12o3l@tiscali.nl> Cc: Andreas Schwab Acked-by: Matt Mackall Acked-by: Mikael Pettersson Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/pagewalk.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/mm/pagewalk.c b/mm/pagewalk.c index 1cf1417ef8b7..0afd2387e507 100644 --- a/mm/pagewalk.c +++ b/mm/pagewalk.c @@ -9,11 +9,15 @@ static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, int err = 0; pte = pte_offset_map(pmd, addr); - do { + for (;;) { err = walk->pte_entry(pte, addr, addr + PAGE_SIZE, private); if (err) break; - } while (pte++, addr += PAGE_SIZE, addr != end); + addr += PAGE_SIZE; + if (addr == end) + break; + pte++; + } pte_unmap(pte); return err;