Re: [PATCH v2] kcov, usb: disable interrupts in kcov_remote_start_usb_softirq

[Greg Kroah-Hartman]

On Tue, May 21, 2024 at 10:43:24PM +0200, andrey.konovalov@xxxxxxxxx wrote:
> From: Andrey Konovalov <andreyknvl@xxxxxxxxx>
> 
> After commit 8fea0c8fda30 ("usb: core: hcd: Convert from tasklet to BH
> workqueue"), usb_giveback_urb_bh() runs in the BH workqueue with
> interrupts enabled.
> 
> Thus, the remote coverage collection section in usb_giveback_urb_bh()->
> __usb_hcd_giveback_urb() might be interrupted, and the interrupt handler
> might invoke __usb_hcd_giveback_urb() again.
> 
> This breaks KCOV, as it does not support nested remote coverage collection
> sections within the same context (neither in task nor in softirq).
> 
> Update kcov_remote_start/stop_usb_softirq() to disable interrupts for the
> duration of the coverage collection section to avoid nested sections in
> the softirq context (in addition to such in the task context, which are
> already handled).
> 
> Reported-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
> Closes: https://lore.kernel.org/linux-usb/0f4d1964-7397-485b-bc48-11c01e2fcbca@xxxxxxxxxxxxxxxxxxx/
> Closes: https://syzkaller.appspot.com/bug?extid=0438378d6f157baae1a2
> Suggested-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
> Fixes: 8fea0c8fda30 ("usb: core: hcd: Convert from tasklet to BH workqueue")
> Acked-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
> Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxx>
> 
> ---
> 
> Changes v1->v2:
> 
> - Fix compiler error when CONFIG_KCOV=n.
> ---
>  drivers/usb/core/hcd.c | 12 ++++++-----
>  include/linux/kcov.h   | 47 ++++++++++++++++++++++++++++++++++--------
>  2 files changed, 45 insertions(+), 14 deletions(-)

Hi,

This is the friendly patch-bot of Greg Kroah-Hartman.  You have sent him
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to these common problems, but in order to save his sanity (he kept
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