Am Montag, 25. Januar 2021, 20:13:24 CET schrieb Heiko Stuebner:
From: Heiko Stuebner heiko.stuebner@theobroma-systems.com
dwc2_hsotg_process_req_status uses ep_from_windex() to retrieve the endpoint for the index provided in the wIndex request param.
In a test-case with a rndis gadget running and sending a malformed packet to it like: dev.ctrl_transfer( 0x82, # bmRequestType 0x00, # bRequest 0x0000, # wValue 0x0001, # wIndex 0x00 # wLength ) it is possible to cause a crash:
[ 217.533022] dwc2 ff300000.usb: dwc2_hsotg_process_req_status: USB_REQ_GET_STATUS [ 217.559003] Unable to handle kernel read from unreadable memory at virtual address 0000000000000088 ... [ 218.313189] Call trace: [ 218.330217] ep_from_windex+0x3c/0x54 [ 218.348565] usb_gadget_giveback_request+0x10/0x20 [ 218.368056] dwc2_hsotg_complete_request+0x144/0x184
This happens because ep_from_windex wants to compare the endpoint direction even if index_to_ep() didn't return an endpoint due to the direction not matching.
The fix is easy insofar that the actual direction check is already happening when calling index_to_ep() which will return NULL if there is no endpoint for the targeted direction, so the offending check can go away completely.
Fixes: c6f5c050e2a7 ("usb: dwc2: gadget: add bi-directional endpoint support") Signed-off-by: Heiko Stuebner heiko.stuebner@theobroma-systems.com Cc: stable@vger.kernel.org
superseeded by v3, which includes an appropriate Reported-by tag and removes an now unused variable (in v2).