On Fri, May 08, 2020 at 07:26:44PM -0700, Bhaumik Bhatt wrote: > From: Hemant Kumar <hemantk@xxxxxxxxxxxxxx> > > 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 driver to memory > 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@xxxxxxxxxxxxxx> > Signed-off-by: Bhaumik Bhatt <bbhatt@xxxxxxxxxxxxxx> > Reviewed-by: Jeffrey Hugo <jhugo@xxxxxxxxxxxxxx> Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx> Thanks, Mani > --- > drivers/bus/mhi/core/main.c | 9 +++++++-- > 1 file changed, 7 insertions(+), 2 deletions(-) > > diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c > index 30798ec..6a80666 100644 > --- a/drivers/bus/mhi/core/main.c > +++ b/drivers/bus/mhi/core/main.c > @@ -514,7 +514,10 @@ 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; > @@ -598,7 +601,9 @@ static int parse_rsc_event(struct mhi_controller *mhi_cntrl, > > result.transaction_status = (ev_code == MHI_EV_CC_OVERFLOW) ? > -EOVERFLOW : 0; > - 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); > result.buf_addr = buf_info->cb_buf; > result.dir = mhi_chan->dir; > > -- > The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, > a Linux Foundation Collaborative Project
