From: John Hubbard <jhubbard@nvidia.com>
To: <dan.carpenter@oracle.com>
Cc: <akpm@linux-foundation.org>, <alex.bou9@gmail.com>,
<gustavoars@kernel.org>, <ira.weiny@intel.com>,
<jhubbard@nvidia.com>, <jrdr.linux@gmail.com>,
<linux-kernel@vger.kernel.org>, <madhuparnabhowmik10@gmail.com>,
<mporter@kernel.crashing.org>, <willy@infradead.org>
Subject: [PATCH] mm/gup: protect unpin_user_pages() against npages==-ERRNO
Date: Wed, 16 Sep 2020 23:57:06 -0700 [thread overview]
Message-ID: <20200917065706.409079-1-jhubbard@nvidia.com> (raw)
In-Reply-To: <20200916100232.GF18329@kadam>
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.
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Souptick Joarder <jrdr.linux@gmail.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---
Hi Dan,
Is is OK to use your signed-off-by here? Since you came up with this.
thanks,
John Hubbard
NVIDIA
mm/gup.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/mm/gup.c b/mm/gup.c
index e5739a1974d5..41d082707016 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -328,6 +328,13 @@ 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
--
2.28.0
next prev parent reply other threads:[~2020-09-17 7:02 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-16 3:42 [linux-next PATCH] rapidio: Fix error handling path Souptick Joarder
2020-09-16 6:37 ` John Hubbard
2020-09-16 10:02 ` Dan Carpenter
2020-09-16 10:07 ` Dan Carpenter
2020-09-16 15:16 ` Ira Weiny
2020-09-16 15:27 ` Dan Carpenter
2020-09-17 6:57 ` John Hubbard [this message]
2020-09-17 7:40 ` [PATCH] mm/gup: protect unpin_user_pages() against npages==-ERRNO Dan Carpenter
2020-09-20 3:03 ` Souptick Joarder
2020-09-20 4:13 ` John Hubbard
2020-09-21 9:34 ` Dan Carpenter
2020-09-17 12:39 ` [linux-next PATCH] rapidio: Fix error handling path Dan Carpenter
2020-09-17 17:34 ` Ira Weiny
2020-09-17 17:47 ` John Hubbard
2020-09-18 2:21 ` Souptick Joarder
2020-09-18 6:33 ` John Hubbard
2020-09-18 2:25 ` Souptick Joarder
2020-09-18 6:15 ` Dan Carpenter
2020-09-16 15:20 ` Ira Weiny
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