mm/pagewalk.c: prevent positive return value of walk_page_test() from being passed...
authorNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Wed, 25 Mar 2015 22:55:14 +0000 (15:55 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Wed, 25 Mar 2015 23:20:30 +0000 (16:20 -0700)
commitf683739539e819e9b821a197d80e52258510837b
tree802b4a45c602f22691d90392fbfcafe97934eadf
parent3fe89b3e2a7bbf3e97657104b9b33a9d81b950b3
mm/pagewalk.c: prevent positive return value of walk_page_test() from being passed to callers

walk_page_test() is purely pagewalk's internal stuff, and its positive
return values are not intended to be passed to the callers of pagewalk.

However, in the current code if the last vma in the do-while loop in
walk_page_range() happens to return a positive value, it leaks outside
walk_page_range().  So the user visible effect is invalid/unexpected
return value (according to the reporter, mbind() causes it.)

This patch fixes it simply by reinitializing the return value after
checked.

Another exposed interface, walk_page_vma(), already returns 0 for such
cases so no problem.

Fixes: fafaa4264eba ("pagewalk: improve vma handling")
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Kazutomo Yoshii <kazutomo.yoshii@gmail.com>
Reported-by: Kazutomo Yoshii <kazutomo.yoshii@gmail.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/pagewalk.c