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Subject[PATCH] usb: musb: fix crash with highmen PIO and usbmon
Date
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->tranfer_buffer to NULL when finished.

Fixes: 8e8a55165469 ("usb: musb: host: Handle highmem in PIO mode")
Signed-off-by: Mans Rullgard <mans@mansr.com>
---
drivers/usb/musb/musb_host.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/musb/musb_host.c b/drivers/usb/musb/musb_host.c
index 1c813c37462a..b67b40de1947 100644
--- a/drivers/usb/musb/musb_host.c
+++ b/drivers/usb/musb/musb_host.c
@@ -1459,8 +1459,10 @@ void musb_host_tx(struct musb *musb, u8 epnum)
qh->segsize = length;

if (qh->use_sg) {
- if (offset + length >= urb->transfer_buffer_length)
+ if (offset + length >= urb->transfer_buffer_length) {
qh->use_sg = false;
+ urb->transfer_buffer = NULL;
+ }
}

musb_ep_select(mbase, epnum);
@@ -1977,8 +1979,10 @@ void musb_host_rx(struct musb *musb, u8 epnum)
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;
--
2.25.1
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