From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga03.intel.com ([134.134.136.65]:25984 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753452AbbHCNEh (ORCPT ); Mon, 3 Aug 2015 09:04:37 -0400 From: Mathias Nyman To: Cc: , Mathias Nyman , Subject: [PATCH 1/2] xhci: fix off by one error in TRB DMA address boundary check Date: Mon, 3 Aug 2015 16:07:48 +0300 Message-Id: <1438607269-8977-2-git-send-email-mathias.nyman@linux.intel.com> In-Reply-To: <1438607269-8977-1-git-send-email-mathias.nyman@linux.intel.com> References: <1438607269-8977-1-git-send-email-mathias.nyman@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: We need to check that a TRB is part of the current segment before calculating its DMA address. Previously a ring segment didn't use a full memory page, and every new ring segment got a new memory page, so the off by one error in checking the upper bound was never seen. Now that we use a full memory page, 256 TRBs (4096 bytes), the off by one didn't catch the case when a TRB was the first element of the next segment. This is triggered if the virtual memory pages for a ring segment are next to each in increasing order where the ring buffer wraps around and causes errors like: [ 106.398223] xhci_hcd 0000:00:14.0: ERROR Transfer event TRB DMA ptr not part of current TD ep_index 0 comp_code 1 [ 106.398230] xhci_hcd 0000:00:14.0: Looking for event-dma fffd3000 trb-start fffd4fd0 trb-end fffd5000 seg-start fffd4000 seg-end fffd4ff0 The trb-end address is one outside the end-seg address. Cc: Tested-by: Arkadiusz Miśkiewicz Signed-off-by: Mathias Nyman --- drivers/usb/host/xhci-ring.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c index 6a8fc52..32f4d56 100644 --- a/drivers/usb/host/xhci-ring.c +++ b/drivers/usb/host/xhci-ring.c @@ -82,7 +82,7 @@ dma_addr_t xhci_trb_virt_to_dma(struct xhci_segment *seg, return 0; /* offset in TRBs */ segment_offset = trb - seg->trbs; - if (segment_offset > TRBS_PER_SEGMENT) + if (segment_offset >= TRBS_PER_SEGMENT) return 0; return seg->dma + (segment_offset * sizeof(*trb)); } -- 1.8.3.2