On Mon, Mar 11, 2019 at 01:02:29PM +0300, Konstantin Khlebnikov wrote:
> free_user() could be called in atomic context.
>
> This patch uses non-sleeping cleanup_srcu_struct_quiesced(). At this stage
> atomic refcount is zero, thus all read-sections should have been ended.
Thanks, I have this in my tree.
-corey
>
> Example:
>
> BUG: sleeping function called from invalid context at kernel/workqueue.c:2856
> in_atomic(): 1, irqs_disabled(): 0, pid: 177, name: ksoftirqd/27
> CPU: 27 PID: 177 Comm: ksoftirqd/27 Not tainted 4.19.25-3 #1
> Hardware name: AIC 1S-HV26-08/MB-DPSB04-06, BIOS IVYBV060 10/21/2015
> Call Trace:
> dump_stack+0x5c/0x7b
> ___might_sleep+0xec/0x110
> __flush_work+0x48/0x1f0
> ? try_to_del_timer_sync+0x4d/0x80
> _cleanup_srcu_struct+0x104/0x140
> free_user+0x18/0x30 [ipmi_msghandler]
> ipmi_free_recv_msg+0x3a/0x50 [ipmi_msghandler]
> deliver_response+0xbd/0xd0 [ipmi_msghandler]
> deliver_local_response+0xe/0x30 [ipmi_msghandler]
> handle_one_recv_msg+0x163/0xc80 [ipmi_msghandler]
> ? dequeue_entity+0xa0/0x960
> handle_new_recv_msgs+0x15c/0x1f0 [ipmi_msghandler]
> tasklet_action_common.isra.22+0x103/0x120
> __do_softirq+0xf8/0x2d7
> run_ksoftirqd+0x26/0x50
> smpboot_thread_fn+0x11d/0x1e0
> kthread+0x103/0x140
> ? sort_range+0x20/0x20
> ? kthread_destroy_worker+0x40/0x40
> ret_from_fork+0x1f/0x40
>
> Fixes: 77f8269606bf ("ipmi: fix use-after-free of user->release_barrier.rda")
> Signed-off-by: Konstantin Khlebnikov <khlebni...@yandex-team.ru>
> Cc: sta...@vger.kernel.org # 4.18
> Cc: Yang Yingliang <yangyingli...@huawei.com>
> Cc: Corey Minyard <cminy...@mvista.com>
> ---
> drivers/char/ipmi/ipmi_msghandler.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/char/ipmi/ipmi_msghandler.c
> b/drivers/char/ipmi/ipmi_msghandler.c
> index e8ba67834746..c35f2bcbaa23 100644
> --- a/drivers/char/ipmi/ipmi_msghandler.c
> +++ b/drivers/char/ipmi/ipmi_msghandler.c
> @@ -1260,7 +1260,12 @@ EXPORT_SYMBOL(ipmi_get_smi_info);
> static void free_user(struct kref *ref)
> {
> struct ipmi_user *user = container_of(ref, struct ipmi_user, refcount);
> - cleanup_srcu_struct(&user->release_barrier);
> +
> + /*
> + * Cleanup without waiting. This could be called in atomic context.
> + * Refcount is zero: all read-sections should have been ended.
> + */
> + cleanup_srcu_struct_quiesced(&user->release_barrier);
> kfree(user);
> }
>
>
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