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

[Jakub Kicinski]

On Mon, 4 Jan 2021 17:58:27 -0500 Sasha Levin wrote:
> 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 :)

Right, the other fix is independent, it came up in review and we decided
to address it separately.