linux-kernel - [PATCH 4.4 08/21] Fix USB CB/CBI storage devices with CONFIG_VMAP

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Message-Id: <20161130092655.349353404@linuxfoundation.org>
Date:   Wed, 30 Nov 2016 10:27:24 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Petr Vandrovec <petr@...drovec.name>,
        Alan Stern <stern@...land.harvard.edu>
Subject: [PATCH 4.4 08/21] Fix USB CB/CBI storage devices with CONFIG_VMAP_STACK=y

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Petr Vandrovec <petr@...drovec.name>

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@...drovec.name>
Acked-by: Alan Stern <stern@...land.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 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
 
 	/* COMMAND STAGE */
 	/* 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_CBI_ADSC, 
 				      USB_TYPE_CLASS | USB_RECIP_INTERFACE, 0, 
-				      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",