Messages in this thread | | | From | Doug Anderson <> | Date | Tue, 17 Jul 2018 12:58:50 -0700 | Subject | Re: [PATCH 2/3] usb: dwc2: host: do not delay retries after successful transfer |
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Hi,
On Fri, Jun 15, 2018 at 4:49 PM, Doug Anderson <dianders@chromium.org> wrote: > Hi, > > On Fri, Jun 15, 2018 at 3:01 PM, Dmitry Torokhov > <dmitry.torokhov@gmail.com> wrote: >> When handling split transactions we should not be delaying retrying >> SSPLIT/CSPLIT after we successfully communicate with the device, so >> let's reset dtd->num_naks counter when handling XFERCOMPL. >> >> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> >> --- >> drivers/usb/dwc2/hcd_intr.c | 1 + >> 1 file changed, 1 insertion(+) > > Reviewed-by: Douglas Anderson <dianders@chromium.org>
Though this looked good, I just tested this myself and found that it corrupts memory. Please do not merge it.
Specifically slub_debug complains of a use after free and sure enough I can see that in one case we call dwc2_xfercomp_isoc_split_in() and it can call dwc2_release_channel() and that can free the qtd. Setting the qtd->num_naks to 0 at the end of the function is a use after free.
I've just tested the same USB peripheral that Dmitry was testing with. I found two things:
* This patch is important for making that peripheral work
* When I move the "qtd->num_naks" to the beginning it's all good.
Dmitry is OOTO at the moment, so I'll re-post this patch with that change.
-Doug
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