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bus: mhi: core: Read transfer length from an event properly 

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@codeaurora.org>
Signed-off-by: Bhaumik Bhatt <bbhatt@codeaurora.org>
Reviewed-by: Jeffrey Hugo <jhugo@codeaurora.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/20200521170249.21795-5-manivannan.sadhasivam@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Hemant Kumar 2020-05-21 22:32:39 +05:30 committed by Greg Kroah-Hartman
parent 0209606850
commit ee75cedf82
1 changed files with 7 additions and 2 deletions
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9
drivers/bus/mhi/core/main.c
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@ -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;