From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable@vger.kernel.org, Li Zefan <lizefan@huawei.com>,
Tejun Heo <tj@kernel.org>
Subject: [ 25/30] cgroup: fix exit() vs rmdir() race
Date: Fri, 1 Mar 2013 11:45:46 -0800 [thread overview]
Message-ID: <20130301194530.732692246@linuxfoundation.org> (raw)
In-Reply-To: <20130301194527.988540148@linuxfoundation.org>
3.0-stable review patch. If anyone has any objections, please let me know.
------------------
From: Li Zefan <lizefan@huawei.com>
commit 71b5707e119653039e6e95213f00479668c79b75 upstream.
In cgroup_exit() put_css_set_taskexit() is called without any lock,
which might lead to accessing a freed cgroup:
thread1 thread2
---------------------------------------------
exit()
cgroup_exit()
put_css_set_taskexit()
atomic_dec(cgrp->count);
rmdir();
/* not safe !! */
check_for_release(cgrp);
rcu_read_lock() can be used to make sure the cgroup is alive.
Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
kernel/cgroup.c | 8 ++++++++
1 file changed, 8 insertions(+)
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -359,12 +359,20 @@ static void __put_css_set(struct css_set
struct cgroup *cgrp = link->cgrp;
list_del(&link->cg_link_list);
list_del(&link->cgrp_link_list);
+
+ /*
+ * We may not be holding cgroup_mutex, and if cgrp->count is
+ * dropped to 0 the cgroup can be destroyed at any time, hence
+ * rcu_read_lock is used to keep it alive.
+ */
+ rcu_read_lock();
if (atomic_dec_and_test(&cgrp->count) &&
notify_on_release(cgrp)) {
if (taskexit)
set_bit(CGRP_RELEASABLE, &cgrp->flags);
check_for_release(cgrp);
}
+ rcu_read_unlock();
kfree(link);
}
next prev parent reply other threads:[~2013-03-01 19:49 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-01 19:45 [ 00/30] 3.0.68-stable review Greg Kroah-Hartman
2013-03-01 19:45 ` [ 01/30] quota: autoload the quota_v2 module for QFMT_VFS_V1 quota format Greg Kroah-Hartman
2013-03-01 19:45 ` [ 02/30] iommu/amd: Initialize device table after dma_ops Greg Kroah-Hartman
2013-03-01 19:45 ` [ 03/30] posix-timer: Dont call idr_find() with out-of-range ID Greg Kroah-Hartman
2013-03-01 19:45 ` [ 04/30] ftrace: Call ftrace cleanup module notifier after all other notifiers Greg Kroah-Hartman
2013-03-01 19:45 ` [ 05/30] doc, xen: Mention earlyprintk=xen in the documentation Greg Kroah-Hartman
2013-03-01 19:45 ` [ 06/30] doc, kernel-parameters: Document console=hvc<n> Greg Kroah-Hartman
2013-03-01 19:45 ` [ 07/30] x86: Make sure we can boot in the case the BDA contains pure garbage Greg Kroah-Hartman
2013-03-01 19:45 ` [ 08/30] target: Add missing mapped_lun bounds checking during make_mappedlun setup Greg Kroah-Hartman
2013-03-01 19:45 ` [ 09/30] ocfs2: ac->ac_allow_chain_relink=0 wont disable group relink Greg Kroah-Hartman
2013-03-01 19:45 ` [ 10/30] xen-blkback: do not leak mode property Greg Kroah-Hartman
2013-03-01 19:45 ` [ 11/30] idr: fix a subtle bug in idr_get_next() Greg Kroah-Hartman
2013-03-01 19:45 ` [ 12/30] firewire: add minor number range check to fw_device_init() Greg Kroah-Hartman
2013-03-01 19:45 ` [ 13/30] sysctl: fix null checking in bin_dn_node_address() Greg Kroah-Hartman
2013-03-01 19:45 ` [ 14/30] media: rc: unlock on error in show_protocols() Greg Kroah-Hartman
2013-03-01 19:45 ` [ 15/30] ext4: fix race in ext4_mb_add_n_trim() Greg Kroah-Hartman
2013-03-01 19:45 ` [ 16/30] svcrpc: make svc_age_temp_xprts enqueue under sv_lock Greg Kroah-Hartman
2013-03-01 19:45 ` [ 17/30] vhost: fix length for cross region descriptor Greg Kroah-Hartman
2013-03-01 19:45 ` [ 18/30] ptrace: introduce signal_wake_up_state() and ptrace_signal_wake_up() Greg Kroah-Hartman
2013-03-01 19:45 ` [ 19/30] ptrace: ensure arch_ptrace/ptrace_request can never race with SIGKILL Greg Kroah-Hartman
2013-03-01 19:45 ` [ 20/30] wake_up_process() should be never used to wakeup a TASK_STOPPED/TRACED task Greg Kroah-Hartman
2013-03-01 19:45 ` [ 21/30] unbreak automounter support on 64-bit kernel with 32-bit userspace (v2) Greg Kroah-Hartman
2013-03-01 19:45 ` [ 22/30] x86: Do not leak kernel page mapping locations Greg Kroah-Hartman
2013-03-01 19:45 ` [ 23/30] x86/apic: Work around boot failure on HP ProLiant DL980 G7 Server systems Greg Kroah-Hartman
2013-03-01 19:45 ` [ 24/30] cpuset: fix cpuset_print_task_mems_allowed() vs rename() race Greg Kroah-Hartman
2013-03-01 19:45 ` Greg Kroah-Hartman [this message]
2013-03-01 19:45 ` [ 26/30] dca: check against empty dca_domains list before unregister provider fix Greg Kroah-Hartman
2013-03-01 19:45 ` [ 27/30] s390/kvm: Fix store status for ACRS/FPRS fix Greg Kroah-Hartman
2013-03-01 19:45 ` [ 28/30] staging: comedi: ni_labpc: correct differential channel sequence for AI commands Greg Kroah-Hartman
2013-03-01 19:45 ` [ 29/30] staging: comedi: ni_labpc: set up command4 register *after* command3 Greg Kroah-Hartman
2013-03-01 19:45 ` [ 30/30] staging: comedi: check s->async for poll(), read() and write() Greg Kroah-Hartman
2013-03-02 3:58 ` [ 00/30] 3.0.68-stable review Shuah Khan
2013-03-03 11:47 ` Satoru Takeuchi
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