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usb: dwc2: limit "maximum packet size" for split-IN transfers

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dwc2_hc_start_transfer() overwrites hc->xfer_len for split-IN transfers.
Drivers may not allocate buffers that are multiples of the endpoint max
packet size, which may cause buffer overruns in the last transfer.

The hardware needs HCTSIZ to be set to a multiple of HCCHAR.MPS, so trim
chan->max_packet in dwc2_assign_and_init_hc().

Signed-off-by: Jonathan Bell <jonathan@raspberrypi.com>
This commit is contained in:
Jonathan Bell
2025-06-11 15:52:40 +01:00
committed by Dom Cobley
parent c60aeaf2e6
commit 21e96f8c3b
1 changed files with 5 additions and 0 deletions
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5
drivers/usb/dwc2/hcd.c
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@@ -2338,6 +2338,7 @@ static void dwc2_hc_init_xfer(struct dwc2_hsotg *hsotg,
else
chan->xfer_buf = urb->setup_packet;
chan->xfer_len = 8;
chan->max_packet = 8;
break;
case DWC2_CONTROL_DATA:
@@ -2621,6 +2622,10 @@ static int dwc2_assign_and_init_hc(struct dwc2_hsotg *hsotg, struct dwc2_qh *qh)
else
chan->do_split = 0;
/* Limit split IN transfers to the remaining buffer space */
if (qh->do_split && chan->ep_is_in)
chan->max_packet = min_t(u32, chan->max_packet, chan->xfer_len);
/* Set the transfer attributes */
dwc2_hc_init_xfer(hsotg, chan, qtd);