patch "usb: gadget: uvc: Fix crash when encoding data for usb request" added to usb-linus

This is a note to let you know that I've just added the patch titled

usb: gadget: uvc: Fix crash when encoding data for usb request

to my usb git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-linus branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.

If you have any questions about this process, please let me know.

From 71d471e3faf90c9674cadc7605ac719e82cb7fac Mon Sep 17 00:00:00 2001
From: Dan Vacura <[email protected]>
Date: Thu, 31 Mar 2022 13:40:23 -0500
Subject: usb: gadget: uvc: Fix crash when encoding data for usb request

During the uvcg_video_pump() process, if an error occurs and uvcg_queue_cancel() is called, the buffer queue will be cleared out, but the current marker (queue->buf_used) of the active buffer (no longer active) is not reset. On the next iteration of uvcg_video_pump() the stale buf_used count will be used and the logic of min((unsigned int)len, buf->bytesused - queue->buf_used) may incorrectly calculate a nbytes size, causing an invalid memory access.

[80802.185460][  T315] configfs-gadget gadget: uvc: VS request completed
with status -18.
[80802.185519][  T315] configfs-gadget gadget: uvc: VS request completed

with status -18.
...
uvcg_queue_cancel() is called and the queue is cleared out, but the marker queue->buf_used is not reset.
...

[80802.262328][ T8682] Unable to handle kernel paging request at virtual
address ffffffc03af9f000
...
...
[80802.263138][ T8682] Call trace:
[80802.263146][ T8682]  __memcpy+0x12c/0x180
[80802.263155][ T8682]  uvcg_video_pump+0xcc/0x1e0
[80802.263165][ T8682]  process_one_work+0x2cc/0x568
[80802.263173][ T8682]  worker_thread+0x28c/0x518
[80802.263181][ T8682]  kthread+0x160/0x170
[80802.263188][ T8682]  ret_from_fork+0x10/0x18
[80802.263198][ T8682] Code: a8c12829 a88130cb a8c130

---
 drivers/usb/gadget/function/uvc_queue.c | 2 ++
 1 file changed, 2 insertions(+)

index d852ac9e47e7..2cda982f3765 100644
@@ -264,6 +264,8 @@ void uvcg_queue_cancel(struct uvc_video_queue *queue, int disconnect)
 		buf->state = UVC_BUF_STATE_ERROR;
 		vb2_buffer_done(&buf->buf.vb2_buf, VB2_BUF_STATE_ERROR);
 	}
+	queue->buf_used = 0;
+
 	/* This must be protected by the irqlock spinlock to avoid race
 	 * conditions between uvc_queue_buffer and the disconnection event that
 	 * could result in an interruptible wait in uvc_dequeue_buffer. Do not

2.35.3