Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759453Ab0HLAEB (ORCPT ); Wed, 11 Aug 2010 20:04:01 -0400 Received: from kroah.org ([198.145.64.141]:60079 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759278Ab0HLADt (ORCPT ); Wed, 11 Aug 2010 20:03:49 -0400 X-Mailbox-Line: From gregkh@clark.site Wed Aug 11 17:01:23 2010 Message-Id: <20100812000123.684503111@clark.site> User-Agent: quilt/0.48-11.2 Date: Wed, 11 Aug 2010 17:00:19 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Marcin Slusarz , Pekka Paalanen , Stuart Bennett , Marcin Kocielnicki , nouveau@lists.freedesktop.org, Ingo Molnar Subject: [04/54] x86, kmmio/mmiotrace: Fix double free of kmmio_fault_pages In-Reply-To: <20100812000249.GA30948@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3767 Lines: 128 2.6.34-stable review patch. If anyone has any objections, please let us know. ------------------ From: Marcin Slusarz commit 8b8f79b927b6b302bb65fb8c56e7a19be5fbdbef upstream. After every iounmap mmiotrace has to free kmmio_fault_pages, but it can't do it directly, so it defers freeing by RCU. It usually works, but when mmiotraced code calls ioremap-iounmap multiple times without sleeping between (so RCU won't kick in and start freeing) it can be given the same virtual address, so at every iounmap mmiotrace will schedule the same pages for release. Obviously it will explode on second free. Fix it by marking kmmio_fault_pages which are scheduled for release and not adding them second time. Signed-off-by: Marcin Slusarz Tested-by: Marcin Kocielnicki Tested-by: Shinpei KATO Acked-by: Pekka Paalanen Cc: Stuart Bennett Cc: Marcin Kocielnicki Cc: nouveau@lists.freedesktop.org LKML-Reference: <20100613215654.GA3829@joi.lan> Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- arch/x86/mm/kmmio.c | 16 +++++++++++++--- arch/x86/mm/testmmiotrace.c | 22 ++++++++++++++++++++++ 2 files changed, 35 insertions(+), 3 deletions(-) --- a/arch/x86/mm/kmmio.c +++ b/arch/x86/mm/kmmio.c @@ -45,6 +45,8 @@ struct kmmio_fault_page { * Protected by kmmio_lock, when linked into kmmio_page_table. */ int count; + + bool scheduled_for_release; }; struct kmmio_delayed_release { @@ -398,8 +400,11 @@ static void release_kmmio_fault_page(uns BUG_ON(f->count < 0); if (!f->count) { disarm_kmmio_fault_page(f); - f->release_next = *release_list; - *release_list = f; + if (!f->scheduled_for_release) { + f->release_next = *release_list; + *release_list = f; + f->scheduled_for_release = true; + } } } @@ -471,8 +476,10 @@ static void remove_kmmio_fault_pages(str prevp = &f->release_next; } else { *prevp = f->release_next; + f->release_next = NULL; + f->scheduled_for_release = false; } - f = f->release_next; + f = *prevp; } spin_unlock_irqrestore(&kmmio_lock, flags); @@ -510,6 +517,9 @@ void unregister_kmmio_probe(struct kmmio kmmio_count--; spin_unlock_irqrestore(&kmmio_lock, flags); + if (!release_list) + return; + drelease = kmalloc(sizeof(*drelease), GFP_ATOMIC); if (!drelease) { pr_crit("leaking kmmio_fault_page objects.\n"); --- a/arch/x86/mm/testmmiotrace.c +++ b/arch/x86/mm/testmmiotrace.c @@ -90,6 +90,27 @@ static void do_test(unsigned long size) iounmap(p); } +/* + * Tests how mmiotrace behaves in face of multiple ioremap / iounmaps in + * a short time. We had a bug in deferred freeing procedure which tried + * to free this region multiple times (ioremap can reuse the same address + * for many mappings). + */ +static void do_test_bulk_ioremapping(void) +{ + void __iomem *p; + int i; + + for (i = 0; i < 10; ++i) { + p = ioremap_nocache(mmio_address, PAGE_SIZE); + if (p) + iounmap(p); + } + + /* Force freeing. If it will crash we will know why. */ + synchronize_rcu(); +} + static int __init init(void) { unsigned long size = (read_far) ? (8 << 20) : (16 << 10); @@ -104,6 +125,7 @@ static int __init init(void) "and writing 16 kB of rubbish in there.\n", size >> 10, mmio_address); do_test(size); + do_test_bulk_ioremapping(); pr_info("All done.\n"); return 0; } -- 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/