Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751869AbbEDVwx (ORCPT ); Mon, 4 May 2015 17:52:53 -0400 Received: from r00tworld.com ([212.85.137.150]:52264 "EHLO r00tworld.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751264AbbEDVwY (ORCPT ); Mon, 4 May 2015 17:52:24 -0400 From: "PaX Team" To: Anisse Astier Date: Mon, 04 May 2015 23:50:13 +0200 MIME-Version: 1.0 Subject: Re: [PATCH v2 3/4] PM / Hibernate: fix SANITIZE_FREED_PAGES Reply-to: pageexec@freemail.hu CC: Andrew Morton , Mel Gorman , "Kirill A. Shutemov" , David Rientjes , Alan Cox , Linus Torvalds , Peter Zijlstra , Brad Spengler , Kees Cook , Andi Kleen , linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Rafael J. Wysocki" , Pavel Machek Message-ID: <5547E995.9980.80084D6@pageexec.freemail.hu> In-reply-to: <1430774218-5311-4-git-send-email-anisse@astier.eu> References: <1430774218-5311-1-git-send-email-anisse@astier.eu>, <1430774218-5311-4-git-send-email-anisse@astier.eu> X-mailer: Pegasus Mail for Windows (4.70) Content-type: text/plain; charset=US-ASCII Content-transfer-encoding: 7BIT Content-description: Mail message body X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-2.1.12 (r00tworld.com [212.85.137.150]); Mon, 04 May 2015 23:50:33 +0200 (CEST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3235 Lines: 100 On 4 May 2015 at 23:16, Anisse Astier wrote: > SANITIZE_FREED_PAGES feature relies on having all pages going through > the free_pages_prepare path in order to be cleared before being used. In > the hibernate use case, pages will automagically appear in the system > without being cleared. is this based on debugging/code reading/discussions with hibernation folks (i see none of them on CC, added them now) or is it just a brute force attempt to fix the symptoms? if the former, it'd be nice to share some more details and have Acks from the code owners. > This fix will make sure free pages are cleared on resume. > > Signed-off-by: Anisse Astier > --- > kernel/power/hibernate.c | 7 ++++++- > kernel/power/power.h | 4 ++++ > kernel/power/snapshot.c | 21 +++++++++++++++++++++ > 3 files changed, 31 insertions(+), 1 deletion(-) > > diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c > index 2329daa..3193b9a 100644 > --- a/kernel/power/hibernate.c > +++ b/kernel/power/hibernate.c > @@ -305,9 +305,14 @@ static int create_image(int platform_mode) > error); > /* Restore control flow magically appears here */ > restore_processor_state(); > - if (!in_suspend) > + if (!in_suspend) { > events_check_enabled = false; > > +#ifdef CONFIG_SANITIZE_FREED_PAGES > + clear_free_pages(); > + printk(KERN_INFO "PM: free pages cleared after restore\n"); > +#endif > + } > platform_leave(platform_mode); > > Power_up: > diff --git a/kernel/power/power.h b/kernel/power/power.h > index ce9b832..26b2101 100644 > --- a/kernel/power/power.h > +++ b/kernel/power/power.h > @@ -92,6 +92,10 @@ extern int create_basic_memory_bitmaps(void); > extern void free_basic_memory_bitmaps(void); > extern int hibernate_preallocate_memory(void); > > +#ifdef CONFIG_SANITIZE_FREED_PAGES > +extern void clear_free_pages(void); > +#endif > + > /** > * Auxiliary structure used for reading the snapshot image data and > * metadata from and writing them to the list of page backup entries > diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c > index 5235dd4..673ade1 100644 > --- a/kernel/power/snapshot.c > +++ b/kernel/power/snapshot.c > @@ -1032,6 +1032,27 @@ void free_basic_memory_bitmaps(void) > pr_debug("PM: Basic memory bitmaps freed\n"); > } > > +#ifdef CONFIG_SANITIZE_FREED_PAGES > +void clear_free_pages(void) > +{ > + struct memory_bitmap *bm = free_pages_map; > + unsigned long pfn; > + > + if (WARN_ON(!(free_pages_map))) > + return; > + > + memory_bm_position_reset(bm); > + pfn = memory_bm_next_pfn(bm); > + while (pfn != BM_END_OF_MAP) { > + if (pfn_valid(pfn)) > + clear_highpage(pfn_to_page(pfn)); > + > + pfn = memory_bm_next_pfn(bm); > + } > + memory_bm_position_reset(bm); > +} > +#endif /* SANITIZE_FREED_PAGES */ > + > /** > * snapshot_additional_pages - estimate the number of additional pages > * be needed for setting up the suspend image data structures for given > -- > 1.9.3 > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/