Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760273Ab0FRKWA (ORCPT ); Fri, 18 Jun 2010 06:22:00 -0400 Received: from hera.kernel.org ([140.211.167.34]:55216 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759757Ab0FRKV5 (ORCPT ); Fri, 18 Jun 2010 06:21:57 -0400 Date: Fri, 18 Jun 2010 10:21:22 GMT From: tip-bot for Marcin Slusarz Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@redhat.com, shinpei@il.is.s.u-tokyo.ac.jp, marcin.slusarz@gmail.com, koriakin@0x04.net, stable@kernel.org, pq@iki.fi, stuart@freedesktop.org, tglx@linutronix.de, mingo@elte.hu Reply-To: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, shinpei@il.is.s.u-tokyo.ac.jp, marcin.slusarz@gmail.com, koriakin@0x04.net, stable@kernel.org, pq@iki.fi, stuart@freedesktop.org, tglx@linutronix.de, mingo@elte.hu In-Reply-To: <20100613215654.GA3829@joi.lan> References: <20100613215654.GA3829@joi.lan> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/mm] x86, kmmio/mmiotrace: Fix double free of kmmio_fault_pages Message-ID: Git-Commit-ID: 8b8f79b927b6b302bb65fb8c56e7a19be5fbdbef X-Mailer: tip-git-log-daemon MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.3 (hera.kernel.org [127.0.0.1]); Fri, 18 Jun 2010 10:21:24 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4135 Lines: 130 Commit-ID: 8b8f79b927b6b302bb65fb8c56e7a19be5fbdbef Gitweb: http://git.kernel.org/tip/8b8f79b927b6b302bb65fb8c56e7a19be5fbdbef Author: Marcin Slusarz AuthorDate: Sun, 13 Jun 2010 23:56:54 +0200 Committer: Ingo Molnar CommitDate: Fri, 18 Jun 2010 11:30:09 +0200 x86, kmmio/mmiotrace: Fix double free of kmmio_fault_pages 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 Cc: LKML-Reference: <20100613215654.GA3829@joi.lan> Signed-off-by: Ingo Molnar --- arch/x86/mm/kmmio.c | 16 +++++++++++++--- arch/x86/mm/testmmiotrace.c | 22 ++++++++++++++++++++++ 2 files changed, 35 insertions(+), 3 deletions(-) diff --git a/arch/x86/mm/kmmio.c b/arch/x86/mm/kmmio.c index 5d0e67f..e5d5e2c 100644 --- 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(unsigned long page, 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(struct rcu_head *head) 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_probe *p) 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"); diff --git a/arch/x86/mm/testmmiotrace.c b/arch/x86/mm/testmmiotrace.c index 8565d94..38868ad 100644 --- 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/