Commit f6837395 authored by Naoya Horiguchi's avatar Naoya Horiguchi Committed by Linus Torvalds

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: fafaa426 ("pagewalk: improve vma handling")
Signed-off-by: default avatarNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: default avatarKazutomo Yoshii <kazutomo.yoshii@gmail.com>
Reported-by: default avatarKazutomo Yoshii <kazutomo.yoshii@gmail.com>
Acked-by: default avatarDavid Rientjes <rientjes@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 3fe89b3e
...@@ -265,8 +265,15 @@ int walk_page_range(unsigned long start, unsigned long end, ...@@ -265,8 +265,15 @@ int walk_page_range(unsigned long start, unsigned long end,
vma = vma->vm_next; vma = vma->vm_next;
err = walk_page_test(start, next, walk); err = walk_page_test(start, next, walk);
if (err > 0) if (err > 0) {
/*
* positive return values are purely for
* controlling the pagewalk, so should never
* be passed to the callers.
*/
err = 0;
continue; continue;
}
if (err < 0) if (err < 0)
break; break;
} }
......
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