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From 7ae8ef63c14ca2fea76c9db5799321f1b3e31c36 Mon Sep 17 00:00:00 2001
From: Jonathan Bell <jonathan@raspberrypi.org>
Date: Tue, 7 Jan 2020 10:08:19 +0000
Subject: [PATCH] dwc_otg: constrain endpoint max packet and transfer
size on split IN
The hcd would unconditionally set the transfer length to the endpoint
packet size for non-isoc IN transfers. If the remaining buffer length
was less than the length of returned data, random memory would get
scribbled over, with bad effects if it crossed a page boundary.
Force a babble error if this happens by limiting the max transfer size
to the available buffer space. DMA will stop writing to memory on a
babble condition.
The hardware expects xfersize to be an integer multiple of maxpacket
size, so override hcchar.b.mps as well.
Signed-off-by: Jonathan Bell <jonathan@raspberrypi.org>
---
drivers/usb/host/dwc_otg/dwc_otg_hcd.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/drivers/usb/host/dwc_otg/dwc_otg_hcd.c
+++ b/drivers/usb/host/dwc_otg/dwc_otg_hcd.c
@@ -1813,7 +1813,7 @@ int fiq_fsm_queue_split_transaction(dwc_
st->nr_errors = 0;
st->hcchar_copy.d32 = 0;
- st->hcchar_copy.b.mps = hc->max_packet;
+ st->hcchar_copy.b.mps = min_t(uint32_t, hc->xfer_len, hc->max_packet);
st->hcchar_copy.b.epdir = hc->ep_is_in;
st->hcchar_copy.b.devaddr = hc->dev_addr;
st->hcchar_copy.b.epnum = hc->ep_num;
@@ -1858,7 +1858,7 @@ int fiq_fsm_queue_split_transaction(dwc_
st->hctsiz_copy.b.pid = hc->data_pid_start;
if (hc->ep_is_in || (hc->xfer_len > hc->max_packet)) {
- hc->xfer_len = hc->max_packet;
+ hc->xfer_len = min_t(uint32_t, hc->xfer_len, hc->max_packet);
} else if (!hc->ep_is_in && (hc->xfer_len > 188)) {
hc->xfer_len = 188;
}
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