From: Johannes Weiner <hannes@saeurebad.de> Date: Mon, 28 Apr 2008 09:11:47 +0000 (-0700) Subject: mm: fix possible off-by-one in walk_pte_range() X-Git-Tag: firefly_0821_release~21501 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=556637cdabcd5918c7d4a1a2679b8f86fc81e891;p=firefly-linux-kernel-4.4.55.git 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 <hannes@saeurebad.de> Cc: Roel Kluin <12o3l@tiscali.nl> Cc: Andreas Schwab <schwab@suse.de> Acked-by: Matt Mackall <mpm@selenic.com> Acked-by: Mikael Pettersson <mikpe@it.uu.se> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> --- 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;