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authorJohn Hubbard <jhubbard@nvidia.com>2020-10-13 16:52:01 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-10-13 18:38:29 -0700
commit146608bb75e6776af4cf42310f583d39311e5334 (patch)
treea6c2a5d836f189b2e2138d7268ec29149fc89016 /mm/gup.c
parent447f3e45c18a8f27018213bcb1b5a0076633f68a (diff)
mm/gup: protect unpin_user_pages() against npages==-ERRNO
As suggested by Dan Carpenter, fortify unpin_user_pages() just a bit, against a typical caller mistake: check if the npages arg is really a -ERRNO value, which would blow up the unpinning loop: WARN and return. If this new WARN_ON() fires, then the system *might* be leaking pages (by leaving them pinned), but probably not. More likely, gup/pup returned a hard -ERRNO error to the caller, who erroneously passed it here. Signed-off-by: John Hubbard <jhubbard@nvidia.com> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Ira Weiny <ira.weiny@intel.com> Cc: Souptick Joarder <jrdr.linux@gmail.com> Link: https://lkml.kernel.org/r/20200917065706.409079-1-jhubbard@nvidia.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/gup.c')
-rw-r--r--mm/gup.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/mm/gup.c b/mm/gup.c
index 32d0e3ca7fbb..ad617e7f22f5 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -329,6 +329,13 @@ void unpin_user_pages(struct page **pages, unsigned long npages)
unsigned long index;
/*
+ * If this WARN_ON() fires, then the system *might* be leaking pages (by
+ * leaving them pinned), but probably not. More likely, gup/pup returned
+ * a hard -ERRNO error to the caller, who erroneously passed it here.
+ */
+ if (WARN_ON(IS_ERR_VALUE(npages)))
+ return;
+ /*
* TODO: this can be optimized for huge pages: if a series of pages is
* physically contiguous and part of the same compound page, then a
* single operation to the head page should suffice.