USB: ums_realtek: do not use stack memory for DMA in __do_config_autodelink

__do_config_autodelink passes the data variable to the transport function.
If the calling functions pass a stack variable, this will eventually trigger
a DMA-API debug backtrace for mapping stack memory in the DMA buffer.  Fix
this by calling kmemdup for the passed data instead.

Signed-off-by: Josh Boyer <jwboyer@redhat.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 7 insertions, 1 deletions

diff --git a/drivers/usb/storage/realtek_cr.c b/drivers/usb/storage/realtek_cr.c
index b1c2fe8b6dcd..84a4bc0cbee4 100644
--- a/drivers/usb/storage/realtek_cr.c
+++ b/drivers/usb/storage/realtek_cr.c
@@ -507,9 +507,14 @@ static int __do_config_autodelink(struct us_data *us, u8 *data, u16 len)
 {
         int retval;
         u8 cmnd[12] = {0};
+        u8 *buf;
 
         US_DEBUGP("%s, addr = 0xfe47, len = %d\n", __FUNCTION__, len);
 
+        buf = kmemdup(data, len, GFP_NOIO);
+        if (!buf)
+                return USB_STOR_TRANSPORT_ERROR;
+
         cmnd[0] = 0xF0;
         cmnd[1] = 0x0E;
         cmnd[2] = 0xfe;
@@ -517,7 +522,8 @@ static int __do_config_autodelink(struct us_data *us, u8 *data, u16 len)
         cmnd[4] = (u8)(len >> 8);
         cmnd[5] = (u8)len;
 
-        retval = rts51x_bulk_transport_special(us, 0, cmnd, 12, data, len, DMA_TO_DEVICE, NULL);
+        retval = rts51x_bulk_transport_special(us, 0, cmnd, 12, buf, len, DMA_TO_DEVICE, NULL);
+        kfree(buf);
         if (retval != USB_STOR_TRANSPORT_GOOD) {
                 return -EIO;
         }