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author | Ioanna Alifieraki <ioanna-maria.alifieraki@canonical.com> | 2021-11-15 16:16:45 +0300 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-12-08 11:04:42 +0300 |
commit | c4618188b15af986c4f43bb63271edc7d07f73aa (patch) | |
tree | d91bdabbded432f91970981e4f10ba47501dab46 /drivers/char | |
parent | 2a715e15588c777cb33a75c2cd38e6f195688f02 (diff) | |
download | linux-c4618188b15af986c4f43bb63271edc7d07f73aa.tar.xz |
ipmi: Move remove_work to dedicated workqueue
commit 1d49eb91e86e8c1c1614c72e3e958b6b7e2472a9 upstream.
Currently when removing an ipmi_user the removal is deferred as a work on
the system's workqueue. Although this guarantees the free operation will
occur in non atomic context, it can race with the ipmi_msghandler module
removal (see [1]) . In case a remove_user work is scheduled for removal
and shortly after ipmi_msghandler module is removed we can end up in a
situation where the module is removed fist and when the work is executed
the system crashes with :
BUG: unable to handle page fault for address: ffffffffc05c3450
PF: supervisor instruction fetch in kernel mode
PF: error_code(0x0010) - not-present page
because the pages of the module are gone. In cleanup_ipmi() there is no
easy way to detect if there are any pending works to flush them before
removing the module. This patch creates a separate workqueue and schedules
the remove_work works on it. When removing the module the workqueue is
drained when destroyed to avoid the race.
[1] https://bugs.launchpad.net/bugs/1950666
Cc: stable@vger.kernel.org # 5.1
Fixes: 3b9a907223d7 (ipmi: fix sleep-in-atomic in free_user at cleanup SRCU user->release_barrier)
Signed-off-by: Ioanna Alifieraki <ioanna-maria.alifieraki@canonical.com>
Message-Id: <20211115131645.25116-1-ioanna-maria.alifieraki@canonical.com>
Signed-off-by: Corey Minyard <cminyard@mvista.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/char')
-rw-r--r-- | drivers/char/ipmi/ipmi_msghandler.c | 13 |
1 files changed, 12 insertions, 1 deletions
diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c index a08f53f208bf..f3a2f228f648 100644 --- a/drivers/char/ipmi/ipmi_msghandler.c +++ b/drivers/char/ipmi/ipmi_msghandler.c @@ -191,6 +191,8 @@ struct ipmi_user { struct work_struct remove_work; }; +struct workqueue_struct *remove_work_wq; + static struct ipmi_user *acquire_ipmi_user(struct ipmi_user *user, int *index) __acquires(user->release_barrier) { @@ -1261,7 +1263,7 @@ static void free_user(struct kref *ref) struct ipmi_user *user = container_of(ref, struct ipmi_user, refcount); /* SRCU cleanup must happen in task context. */ - schedule_work(&user->remove_work); + queue_work(remove_work_wq, &user->remove_work); } static void _ipmi_destroy_user(struct ipmi_user *user) @@ -5153,6 +5155,13 @@ static int ipmi_init_msghandler(void) atomic_notifier_chain_register(&panic_notifier_list, &panic_block); + remove_work_wq = create_singlethread_workqueue("ipmi-msghandler-remove-wq"); + if (!remove_work_wq) { + pr_err("unable to create ipmi-msghandler-remove-wq workqueue"); + rv = -ENOMEM; + goto out; + } + initialized = true; out: @@ -5178,6 +5187,8 @@ static void __exit cleanup_ipmi(void) int count; if (initialized) { + destroy_workqueue(remove_work_wq); + atomic_notifier_chain_unregister(&panic_notifier_list, &panic_block); |