3.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Johan Hovold <jhovold@xxxxxxxxx>
commit d8a083cc746664916d9d36ed9e4d08a29525f245 upstream.
Fix race in mos7840_get_reg which unconditionally manipulated the
control urb (which may already be in use) by adding a control-urb busy
flag.
Signed-off-by: Johan Hovold <jhovold@xxxxxxxxx>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Cc: Yang Yingliang <yangyingliang@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/usb/serial/mos7840.c | 18 ++++++++++++++++--
1 file changed, 16 insertions(+), 2 deletions(-)
--- a/drivers/usb/serial/mos7840.c
+++ b/drivers/usb/serial/mos7840.c
@@ -185,6 +185,10 @@
#define URB_TRANSFER_BUFFER_SIZE 32 /* URB Size */
+enum mos7840_flag {
+ MOS7840_FLAG_CTRL_BUSY,
+};
+
static const struct usb_device_id moschip_port_id_table[] = {
{USB_DEVICE(USB_VENDOR_ID_MOSCHIP, MOSCHIP_DEVICE_ID_7840)},
{USB_DEVICE(USB_VENDOR_ID_MOSCHIP, MOSCHIP_DEVICE_ID_7820)},
@@ -258,6 +262,8 @@ struct moschip_port {
struct urb *write_urb_pool[NUM_URBS];
char busy[NUM_URBS];
bool read_urb_busy;
+
+ unsigned long flags;
};
@@ -519,11 +525,11 @@ static void mos7840_control_callback(str
/* this urb is terminated, clean up */
dbg("%s - urb shutting down with status: %d", __func__,
status);
- return;
+ goto out;
default:
dbg("%s - nonzero urb status received: %d", __func__,
status);
- return;
+ goto out;
}
dbg("%s urb buffer size is %d", __func__, urb->actual_length);
@@ -536,6 +542,8 @@ static void mos7840_control_callback(str
mos7840_handle_new_msr(mos7840_port, regval);
else if (mos7840_port->MsrLsr == 1)
mos7840_handle_new_lsr(mos7840_port, regval);
+out:
+ clear_bit_unlock(MOS7840_FLAG_CTRL_BUSY, &mos7840_port->flags);
}
static int mos7840_get_reg(struct moschip_port *mcs, __u16 Wval, __u16 reg,
@@ -546,6 +554,9 @@ static int mos7840_get_reg(struct moschi
unsigned char *buffer = mcs->ctrl_buf;
int ret;
+ if (test_and_set_bit_lock(MOS7840_FLAG_CTRL_BUSY, &mcs->flags))
+ return -EBUSY;
+
dr->bRequestType = MCS_RD_RTYPE;
dr->bRequest = MCS_RDREQ;
dr->wValue = cpu_to_le16(Wval); /* 0 */
@@ -557,6 +568,9 @@ static int mos7840_get_reg(struct moschi
mos7840_control_callback, mcs);
mcs->control_urb->transfer_buffer_length = 2;
ret = usb_submit_urb(mcs->control_urb, GFP_ATOMIC);
+ if (ret)
+ clear_bit_unlock(MOS7840_FLAG_CTRL_BUSY, &mcs->flags);
+
return ret;
}
--
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