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Subject[PATCH 5.5 154/170] usb: musb: fix crash with highmen PIO and usbmon
Date
From: Mans Rullgard <mans@mansr.com>

commit 52974d94a206ce428d9d9b6eaa208238024be82a upstream.

When handling a PIO bulk transfer with highmem buffer, a temporary
mapping is assigned to urb->transfer_buffer. After the transfer is
complete, an invalid address is left behind in this pointer. This is
not ordinarily a problem since nothing touches that buffer before the
urb is released. However, when usbmon is active, usbmon_urb_complete()
calls (indirectly) mon_bin_get_data() which does access the transfer
buffer if it is set. To prevent an invalid memory access here, reset
urb->transfer_buffer to NULL when finished (musb_host_rx()), or do not
set it at all (musb_host_tx()).

Fixes: 8e8a55165469 ("usb: musb: host: Handle highmem in PIO mode")
Signed-off-by: Mans Rullgard <mans@mansr.com>
Cc: stable@vger.kernel.org
Signed-off-by: Bin Liu <b-liu@ti.com>
Link: https://lore.kernel.org/r/20200316211136.2274-8-b-liu@ti.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/usb/musb/musb_host.c | 17 +++++------------
1 file changed, 5 insertions(+), 12 deletions(-)

--- a/drivers/usb/musb/musb_host.c
+++ b/drivers/usb/musb/musb_host.c
@@ -1462,10 +1462,7 @@ done:
* We need to map sg if the transfer_buffer is
* NULL.
*/
- if (!urb->transfer_buffer)
- qh->use_sg = true;
-
- if (qh->use_sg) {
+ if (!urb->transfer_buffer) {
/* sg_miter_start is already done in musb_ep_program */
if (!sg_miter_next(&qh->sg_miter)) {
dev_err(musb->controller, "error: sg list empty\n");
@@ -1473,9 +1470,8 @@ done:
status = -EINVAL;
goto done;
}
- urb->transfer_buffer = qh->sg_miter.addr;
length = min_t(u32, length, qh->sg_miter.length);
- musb_write_fifo(hw_ep, length, urb->transfer_buffer);
+ musb_write_fifo(hw_ep, length, qh->sg_miter.addr);
qh->sg_miter.consumed = length;
sg_miter_stop(&qh->sg_miter);
} else {
@@ -1484,11 +1480,6 @@ done:

qh->segsize = length;

- if (qh->use_sg) {
- if (offset + length >= urb->transfer_buffer_length)
- qh->use_sg = false;
- }
-
musb_ep_select(mbase, epnum);
musb_writew(epio, MUSB_TXCSR,
MUSB_TXCSR_H_WZC_BITS | MUSB_TXCSR_TXPKTRDY);
@@ -2003,8 +1994,10 @@ finish:
urb->actual_length += xfer_len;
qh->offset += xfer_len;
if (done) {
- if (qh->use_sg)
+ if (qh->use_sg) {
qh->use_sg = false;
+ urb->transfer_buffer = NULL;
+ }

if (urb->status == -EINPROGRESS)
urb->status = status;

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