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Subject[PATCH 13/16] mm: validate get_user_pages_fast flags
Date
We can only deal with FOLL_WRITE and/or FOLL_LONGTERM in
get_user_pages_fast, so reject all other flags.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
mm/gup.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/mm/gup.c b/mm/gup.c
index c8da7764de9c..53b50c63ba51 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2316,6 +2316,9 @@ int get_user_pages_fast(unsigned long start, int nr_pages,
unsigned long addr, len, end;
int nr = 0, ret = 0;

+ if (WARN_ON_ONCE(gup_flags & ~(FOLL_WRITE | FOLL_LONGTERM)))
+ return -EINVAL;
+
start = untagged_addr(start) & PAGE_MASK;
addr = start;
len = (unsigned long) nr_pages << PAGE_SHIFT;
--
2.20.1
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