From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932148Ab2HUQiG (ORCPT ); Tue, 21 Aug 2012 12:38:06 -0400 Received: from terminus.zytor.com ([198.137.202.10]:33100 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756147Ab2HUQiC (ORCPT ); Tue, 21 Aug 2012 12:38:02 -0400 Date: Tue, 21 Aug 2012 09:37:44 -0700 From: tip-bot for Oleg Nesterov Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@kernel.org, torvalds@linux-foundation.org, wcohen@redhat.com, anton@redhat.com, srikar@linux.vnet.ibm.com, tglx@linutronix.de, oleg@redhat.com Reply-To: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, wcohen@redhat.com, anton@redhat.com, srikar@linux.vnet.ibm.com, tglx@linutronix.de, oleg@redhat.com In-Reply-To: <20120819171042.GB26957@redhat.com> References: <20120819171042.GB26957@redhat.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:perf/urgent] uprobes: Fix mmap_region()'s mm-> mm_rb corruption if uprobe_mmap() fails Git-Commit-ID: c7a3a88c938fbe3d70c2278e082b80eb830d1c58 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.6 (terminus.zytor.com [127.0.0.1]); Tue, 21 Aug 2012 09:37:49 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: c7a3a88c938fbe3d70c2278e082b80eb830d1c58 Gitweb: http://git.kernel.org/tip/c7a3a88c938fbe3d70c2278e082b80eb830d1c58 Author: Oleg Nesterov AuthorDate: Sun, 19 Aug 2012 19:10:42 +0200 Committer: Ingo Molnar CommitDate: Tue, 21 Aug 2012 11:48:12 +0200 uprobes: Fix mmap_region()'s mm->mm_rb corruption if uprobe_mmap() fails This patch fixes: https://bugzilla.redhat.com/show_bug.cgi?id=843640 If mmap_region()->uprobe_mmap() fails, unmap_and_free_vma path does unmap_region() but does not remove the soon-to-be-freed vma from rb tree. Actually there are more problems but this is how William noticed this bug. Perhaps we could do do_munmap() + return in this case, but in fact it is simply wrong to abort if uprobe_mmap() fails. Until at least we move the !UPROBE_COPY_INSN code from install_breakpoint() to uprobe_register(). For example, uprobe_mmap()->install_breakpoint() can fail if the probed insn is not supported (remember, uprobe_register() succeeds if nobody mmaps inode/offset), mmap() should not fail in this case. dup_mmap()->uprobe_mmap() is wrong too by the same reason, fork() can race with uprobe_register() and fail for no reason if it wins the race and does install_breakpoint() first. And, if nothing else, both mmap_region() and dup_mmap() return success if uprobe_mmap() fails. Change them to ignore the error code from uprobe_mmap(). Reported-and-tested-by: William Cohen Signed-off-by: Oleg Nesterov Acked-by: Srikar Dronamraju Cc: # v3.5 Cc: Anton Arapov Cc: William Cohen Cc: Linus Torvalds Link: http://lkml.kernel.org/r/20120819171042.GB26957@redhat.com Signed-off-by: Ingo Molnar --- kernel/fork.c | 4 ++-- mm/mmap.c | 5 ++--- 2 files changed, 4 insertions(+), 5 deletions(-) diff --git a/kernel/fork.c b/kernel/fork.c index 3bd2280..2c8857e 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -455,8 +455,8 @@ static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm) if (retval) goto out; - if (file && uprobe_mmap(tmp)) - goto out; + if (file) + uprobe_mmap(tmp); } /* a new mm has just been created */ arch_dup_mmap(oldmm, mm); diff --git a/mm/mmap.c b/mm/mmap.c index e3e8691..52e08fc 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1356,9 +1356,8 @@ out: } else if ((flags & MAP_POPULATE) && !(flags & MAP_NONBLOCK)) make_pages_present(addr, addr + len); - if (file && uprobe_mmap(vma)) - /* matching probes but cannot insert */ - goto unmap_and_free_vma; + if (file) + uprobe_mmap(vma); return addr;