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Message-ID: <lsq.1444349547.157050950@decadent.org.uk> Date: Fri, 09 Oct 2015 01:12:27 +0100 From: Ben Hutchings <ben@...adent.org.uk> To: linux-kernel@...r.kernel.org, stable@...r.kernel.org CC: akpm@...ux-foundation.org, "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>, "Arkadiusz Miśkiewicz" <arekm@...en.pl>, "Mathias Nyman" <mathias.nyman@...ux.intel.com> Subject: [PATCH 3.2 011/107] xhci: fix off by one error in TRB DMA address boundary check 3.2.72-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Mathias Nyman <mathias.nyman@...ux.intel.com> commit 7895086afde2a05fa24a0e410d8e6b75ca7c8fdd upstream. 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. Tested-by: Arkadiusz Miśkiewicz <arekm@...en.pl> Signed-off-by: Mathias Nyman <mathias.nyman@...ux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org> Signed-off-by: Ben Hutchings <ben@...adent.org.uk> --- drivers/usb/host/xhci-ring.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/usb/host/xhci-ring.c +++ b/drivers/usb/host/xhci-ring.c @@ -85,7 +85,7 @@ dma_addr_t xhci_trb_virt_to_dma(struct x 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)); } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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