* [BUG] xen: Two possible sleep-in-atomic-context bugs in bind_evtchn_to_irqhandler()
@ 2018-06-20 2:49 Jia-Ju Bai
2018-06-20 6:57 ` Juergen Gross
0 siblings, 1 reply; 2+ messages in thread
From: Jia-Ju Bai @ 2018-06-20 2:49 UTC (permalink / raw)
To: Boris Ostrovsky, jgross; +Cc: xen-devel, Linux Kernel Mailing List
The driver may sleep with holding a spinlock.
The function call paths (from bottom to top) in Linux-4.16.7 are:
[FUNC] mutex_lock_nested --> can sleep
drivers/xen/events/events_base.c, 839: mutex_lock_nested in
bind_evtchn_to_irq
drivers/xen/events/events_base.c, 1030: bind_evtchn_to_irq in
bind_evtchn_to_irqhandler
drivers/xen/pvcalls-front.c, 371: bind_evtchn_to_irqhandler in create_active
drivers/xen/pvcalls-front.c, 417: create_active in pvcalls_front_connect
drivers/xen/pvcalls-front.c, 410: spin_lock in pvcalls_front_connect
[FUNC] request_irq --> can sleep
drivers/xen/events/events_base.c, 1003: request_irq in
bind_evtchn_to_irqhandler
drivers/xen/pvcalls-front.c, 371: bind_evtchn_to_irqhandler in create_active
drivers/xen/pvcalls-front.c, 417: create_active in pvcalls_front_connect
drivers/xen/pvcalls-front.c, 410: spin_lock in pvcalls_front_connect
These bugs are found by my static analysis tool (DSAC-2) and checked by my
code review.
I do not know how to correctly fix these bugs, so I just report them.
Maybe create_active() should not be called with holding a spinlock.
Best wishes,
Jia-Ju Bai
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [BUG] xen: Two possible sleep-in-atomic-context bugs in bind_evtchn_to_irqhandler()
2018-06-20 2:49 [BUG] xen: Two possible sleep-in-atomic-context bugs in bind_evtchn_to_irqhandler() Jia-Ju Bai
@ 2018-06-20 6:57 ` Juergen Gross
0 siblings, 0 replies; 2+ messages in thread
From: Juergen Gross @ 2018-06-20 6:57 UTC (permalink / raw)
To: Jia-Ju Bai, Stefano Stabellini; +Cc: Boris Ostrovsky, Linux Kernel Mailing List
On 20/06/18 04:49, Jia-Ju Bai wrote:
> The driver may sleep with holding a spinlock.
> The function call paths (from bottom to top) in Linux-4.16.7 are:
>
> [FUNC] mutex_lock_nested --> can sleep
> drivers/xen/events/events_base.c, 839: mutex_lock_nested in
> bind_evtchn_to_irq
> drivers/xen/events/events_base.c, 1030: bind_evtchn_to_irq in
> bind_evtchn_to_irqhandler
> drivers/xen/pvcalls-front.c, 371: bind_evtchn_to_irqhandler in
> create_active
> drivers/xen/pvcalls-front.c, 417: create_active in pvcalls_front_connect
> drivers/xen/pvcalls-front.c, 410: spin_lock in pvcalls_front_connect
>
> [FUNC] request_irq --> can sleep
> drivers/xen/events/events_base.c, 1003: request_irq in
> bind_evtchn_to_irqhandler
> drivers/xen/pvcalls-front.c, 371: bind_evtchn_to_irqhandler in
> create_active
> drivers/xen/pvcalls-front.c, 417: create_active in pvcalls_front_connect
> drivers/xen/pvcalls-front.c, 410: spin_lock in pvcalls_front_connect
>
> These bugs are found by my static analysis tool (DSAC-2) and checked by my
> code review.
>
> I do not know how to correctly fix these bugs, so I just report them.
> Maybe create_active() should not be called with holding a spinlock.
Right, I think calling create_active() should be done before taking the
lock. Stefano, what do you think?
Juergen
^ permalink raw reply [flat|nested] 2+ messages in thread
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2018-06-20 2:49 [BUG] xen: Two possible sleep-in-atomic-context bugs in bind_evtchn_to_irqhandler() Jia-Ju Bai
2018-06-20 6:57 ` Juergen Gross
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