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Sun, 13 Sep 2020 07:32:59 -0700 (PDT) Received: from jordon-HP-15-Notebook-PC.domain.name ([122.167.45.202]) by smtp.gmail.com with ESMTPSA id kf10sm6618257pjb.2.2020.09.13.07.32.56 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Sun, 13 Sep 2020 07:32:58 -0700 (PDT) From: Souptick Joarder To: akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Souptick Joarder , John Hubbard Subject: [PATCH] mm/gup.c: Handling ERR within unpin_user_pages() Date: Sun, 13 Sep 2020 20:02:35 +0530 Message-Id: <1600007555-11650-1-git-send-email-jrdr.linux@gmail.com> X-Mailer: git-send-email 1.9.1 X-Rspamd-Queue-Id: C3650100E6912 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam01 X-Bogosity: Ham, tests=bogofilter, spamicity=0.020335, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: It is possible that a buggy caller of unpin_user_pages() (specially in error handling path) may end up calling it with npages < 0 which is unnecessary. This can be fixed by adding extra check inside unpin_user_pages(). Signed-off-by: Souptick Joarder Cc: John Hubbard --- mm/gup.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/mm/gup.c b/mm/gup.c index 0b5c308b..2e19bd6 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -328,6 +328,9 @@ void unpin_user_pages(struct page **pages, unsigned long npages) { unsigned long index; + if (WARN_ON_ONCE(npages < 0)) + 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