From: Mathias Nyman <mathias.nyman@linux.intel.com>
To: <gregkh@linuxfoundation.org>
Cc: <linux-usb@vger.kernel.org>,
Mathias Nyman <mathias.nyman@linux.intel.com>,
"# v5 . 2" <stable@vger.kernel.org>,
Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Subject: [PATCH] xhci: Fix crash if scatter gather is used with Immediate Data Transfer (IDT).
Date: Thu, 25 Jul 2019 11:54:21 +0300 [thread overview]
Message-ID: <1564044861-1445-1-git-send-email-mathias.nyman@linux.intel.com> (raw)
A second regression was found in the immediate data transfer (IDT)
support which was added to 5.2 kernel
IDT is used to transfer small amounts of data (up to 8 bytes) in the
field normally used for data dma address, thus avoiding dma mapping.
If the data was not already dma mapped, then IDT support assumed data was
in urb->transfer_buffer, and did not take into accound that even
small amounts of data (8 bytes) can be in a scatterlist instead.
This caused a NULL pointer dereference when sg_dma_len() was used
with non-dma mapped data.
Solve this by not using IDT if scatter gather buffer list is used.
Fixes: 33e39350ebd2 ("usb: xhci: add Immediate Data Transfer support")
Cc: <stable@vger.kernel.org> # v5.2
Reported-by: Maik Stohn <maik.stohn@seal-one.com>
Tested-by: Maik Stohn <maik.stohn@seal-one.com>
CC: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
---
drivers/usb/host/xhci.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index 7a26496..f5c4144 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -2175,7 +2175,8 @@ static inline bool xhci_urb_suitable_for_idt(struct urb *urb)
if (!usb_endpoint_xfer_isoc(&urb->ep->desc) && usb_urb_dir_out(urb) &&
usb_endpoint_maxp(&urb->ep->desc) >= TRB_IDT_MAX_SIZE &&
urb->transfer_buffer_length <= TRB_IDT_MAX_SIZE &&
- !(urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP))
+ !(urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP) &&
+ !urb->num_sgs)
return true;
return false;
--
2.7.4
reply other threads:[~2019-07-25 8:53 UTC|newest]
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