Messages in this thread | | | Subject | Re: [PATCH v2 3/8] bus: mhi: core: Read transfer length from an event properly | From | Jeffrey Hugo <> | Date | Tue, 28 Apr 2020 08:50:04 -0600 |
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On 4/27/2020 8:59 PM, Bhaumik Bhatt wrote: > From: Hemant Kumar <hemantk@codeaurora.org> > > When MHI Driver receives an EOT event, it reads xfer_len from the > event in the last TRE. The value is under control of the MHI device > and never validated by Host MHI driver. The value should never be > larger than the real size of the buffer but a malicious device can > set the value 0xFFFF as maximum. This causes device to memory
The device will overflow, or the driver?
> overflow (both read or write). Fix this issue by reading minimum of > transfer length from event and the buffer length provided. > > Signed-off-by: Hemant Kumar <hemantk@codeaurora.org> > Signed-off-by: Bhaumik Bhatt <bbhatt@codeaurora.org> > --- > drivers/bus/mhi/core/main.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c > index 1ccd4cc..3d468d9 100644 > --- a/drivers/bus/mhi/core/main.c > +++ b/drivers/bus/mhi/core/main.c > @@ -521,7 +521,10 @@ static int parse_xfer_event(struct mhi_controller *mhi_cntrl, > mhi_cntrl->unmap_single(mhi_cntrl, buf_info); > > result.buf_addr = buf_info->cb_buf; > - result.bytes_xferd = xfer_len; > + > + /* truncate to buf len if xfer_len is larger */ > + result.bytes_xferd = > + min_t(u16, xfer_len, buf_info->len); > mhi_del_ring_element(mhi_cntrl, buf_ring); > mhi_del_ring_element(mhi_cntrl, tre_ring); > local_rp = tre_ring->rp; >
-- Jeffrey Hugo Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.
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