From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E47C3C4363D for ; Tue, 13 Oct 2020 23:52:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AFFF42222E for ; Tue, 13 Oct 2020 23:52:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1602633142; bh=5q4yq1WqrA1fxYozEfb1M0AZwwgjjeqV0S0X3cFTOAs=; h=Date:From:To:Subject:In-Reply-To:Reply-To:List-ID:From; b=NUH8MFhDA6SD2sygXrZzolzGF9Hq3f54x/al2hZAUwG4XoSG5CT9JpgNHHq9uACoY YDLVsyXVVjLGBLhiwipvRQrOFWTRRzyJXF5hxXdxTAc5GRa6+UFwwX2Zu0YE3d85pO iSUW+rj3y9x5kRxgEnBZkur91gGgGKAYpEOlFkkM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728768AbgJMXwW (ORCPT ); Tue, 13 Oct 2020 19:52:22 -0400 Received: from mail.kernel.org ([198.145.29.99]:36918 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728748AbgJMXwC (ORCPT ); Tue, 13 Oct 2020 19:52:02 -0400 Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 362C422200; Tue, 13 Oct 2020 23:52:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1602633122; bh=5q4yq1WqrA1fxYozEfb1M0AZwwgjjeqV0S0X3cFTOAs=; h=Date:From:To:Subject:In-Reply-To:From; b=xqcGkgKJbGa1y4iIfQlVMfEI1rqpprAVTRPec32R/Fq1a1HA8EP8tKZ3xD5dGntZs 9xIqIb2IAMaX3usC3wTuxlRXW7AQIARol41CErmAlB13bW8NtlHcWTxp2s+v8HQDrC 8s7Ubzb0HsBJfbuqz8SmPaGyzHaYBDvIBJf/0pa0= Date: Tue, 13 Oct 2020 16:52:01 -0700 From: Andrew Morton To: akpm@linux-foundation.org, dan.carpenter@oracle.com, ira.weiny@intel.com, jhubbard@nvidia.com, jrdr.linux@gmail.com, linux-mm@kvack.org, mm-commits@vger.kernel.org, torvalds@linux-foundation.org Subject: [patch 067/181] mm/gup: protect unpin_user_pages() against npages==-ERRNO Message-ID: <20201013235201.FZrZ9P783%akpm@linux-foundation.org> In-Reply-To: <20201013164658.3bfd96cc224d8923e66a9f4e@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: John Hubbard Subject: 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. Link: https://lkml.kernel.org/r/20200917065706.409079-1-jhubbard@nvidia.com Signed-off-by: John Hubbard Signed-off-by: Dan Carpenter Cc: Ira Weiny Cc: Souptick Joarder Signed-off-by: Andrew Morton --- mm/gup.c | 7 +++++++ 1 file changed, 7 insertions(+) --- a/mm/gup.c~mm-gup-protect-unpin_user_pages-against-npages==-errno +++ a/mm/gup.c @@ -329,6 +329,13 @@ void unpin_user_pages(struct page **page 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. _