Re: [PATCH 5.10 01/63] net/sched: sch_taprio: reset child qdiscs before freeing them

[Sasha Levin]

On Mon, Jan 04, 2021 at 04:56:54PM +0100, Greg Kroah-Hartman wrote:
> From: Davide Caratti <dcaratti@xxxxxxxxxx>
>
> [ Upstream commit 44d4775ca51805b376a8db5b34f650434a08e556 ]
>
> syzkaller shows that packets can still be dequeued while taprio_destroy()
> is running. Let sch_taprio use the reset() function to cancel the advance
> timer and drop all skbs from the child qdiscs.
>
> Fixes: 5a781ccbd19e ("tc: Add support for configuring the taprio scheduler")
> Link: https://syzkaller.appspot.com/bug?id=f362872379bf8f0017fb667c1ab158f2d1e764ae
> Reported-by: syzbot+8971da381fb5a31f542d@xxxxxxxxxxxxxxxxxxxxxxxxx
> Signed-off-by: Davide Caratti <dcaratti@xxxxxxxxxx>
> Acked-by: Vinicius Costa Gomes <vinicius.gomes@xxxxxxxxx>
> Link: https://lore.kernel.org/r/63b6d79b0e830ebb0283e020db4df3cdfdfb2b94.1608142843.git.dcaratti@xxxxxxxxxx
> Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

I noticed that there's a fix for this patch going through netdev (but
not yet in Linus's tree). The fix reads to me like it fixes a missed
corner case by this patch rather than this patch being incorrect, so
I'll leave this patch in. If anyone disagrees please speak up :)

--
Thanks,
Sasha