The patch titled
Subject: mm/gup: fix omission of check on FOLL_LONGTERM in get_user_pages_fast()
has been added to the -mm tree. Its filename is
mm-gup-fix-omission-of-check-on-foll_longterm-in-get_user_pages_fast.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-gup-fix-omission-of-check-on-foll_longterm-in-get_user_pages_fast.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-gup-fix-omission-of-check-on-foll_longterm-in-get_user_pages_fast.patch
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------------------------------------------------------
From: Pingfan Liu <kernelfans@xxxxxxxxx>
Subject: mm/gup: fix omission of check on FOLL_LONGTERM in get_user_pages_fast()
FOLL_LONGTERM is checked in the slow path via __gup_longterm_unlocked().
But it is not checked in the fast path, which means a possible leak of CMA
pages to longterm pinned requirement through this crack.
Place a check in the fast path.
Link: http://lkml.kernel.org/r/1559725820-26138-1-git-send-email-kernelfans@xxxxxxxxx
Signed-off-by: Pingfan Liu <kernelfans@xxxxxxxxx>
Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Ira Weiny <ira.weiny@xxxxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: John Hubbard <jhubbard@xxxxxxxxxx>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxx>
Cc: Keith Busch <keith.busch@xxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/gup.c | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)
--- a/mm/gup.c~mm-gup-fix-omission-of-check-on-foll_longterm-in-get_user_pages_fast
+++ a/mm/gup.c
@@ -2197,6 +2197,26 @@ static int __gup_longterm_unlocked(unsig
return ret;
}
+#ifdef CONFIG_CMA
+static inline int reject_cma_pages(int nr_pinned, struct page **pages)
+{
+ int i;
+
+ for (i = 0; i < nr_pinned; i++)
+ if (is_migrate_cma_page(pages[i])) {
+ put_user_pages(pages + i, nr_pinned - i);
+ return i;
+ }
+
+ return nr_pinned;
+}
+#else
+static inline int reject_cma_pages(int nr_pinned, struct page **pages)
+{
+ return nr_pinned;
+}
+#endif
+
/**
* get_user_pages_fast() - pin user pages in memory
* @start: starting user address
@@ -2237,6 +2257,9 @@ int get_user_pages_fast(unsigned long st
ret = nr;
}
+ if (unlikely(gup_flags & FOLL_LONGTERM) && nr)
+ nr = reject_cma_pages(nr, pages);
+
if (nr < nr_pages) {
/* Try to get the remaining pages with get_user_pages */
start += nr << PAGE_SHIFT;
_
Patches currently in -mm which might be from kernelfans@xxxxxxxxx are
mm-gup-fix-omission-of-check-on-foll_longterm-in-get_user_pages_fast.patch
mm-gup-rename-nr-as-nr_pinned-in-get_user_pages_fast.patch
