[PATCH 3.16 229/306] Fix USB CB/CBI storage devices with CONFIG_VMAP_STACK=y

From: Ben Hutchings
Date: Wed Feb 15 2017 - 19:12:28 EST

3.16.40-rc1 review patch. If anyone has any objections, please let me know.


From: Petr Vandrovec <petr@xxxxxxxxxxxxxx>

commit 2ce9d2272b98743b911196c49e7af5841381c206 upstream.

Some code (all error handling) submits CDBs that are allocated
on the stack. This breaks with CB/CBI code that tries to create
URB directly from SCSI command buffer - which happens to be in
vmalloced memory with vmalloced kernel stacks.

Let's make copy of the command in usb_stor_CB_transport.

Signed-off-by: Petr Vandrovec <petr@xxxxxxxxxxxxxx>
Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
drivers/usb/storage/transport.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)

--- a/drivers/usb/storage/transport.c
+++ b/drivers/usb/storage/transport.c
@@ -919,10 +919,15 @@ int usb_stor_CB_transport(struct scsi_cm

/* let's send the command via the control pipe */
+ /*
+ * Command is sometime (f.e. after scsi_eh_prep_cmnd) on the stack.
+ * Stack may be vmallocated. So no DMA for us. Make a copy.
+ */
+ memcpy(us->iobuf, srb->cmnd, srb->cmd_len);
result = usb_stor_ctrl_transfer(us, us->send_ctrl_pipe,
- us->ifnum, srb->cmnd, srb->cmd_len);
+ us->ifnum, us->iobuf, srb->cmd_len);

/* check the return code for the command */
usb_stor_dbg(us, "Call to usb_stor_ctrl_transfer() returned %d\n",