On 2020-05-04 07:33, Jeffrey Hugo wrote:
On 5/1/2020 8:32 PM, Bhaumik Bhatt wrote:
While writing any sequence or session identifiers, it is possible that
the host could write a zero value, whereas only non-zero values should
be supported writes to those registers. Ensure that the host does not
write a non-zero value for them and also log them in debug messages.
Suggested-by: Jeffrey Hugo <jhugo@xxxxxxxxxxxxxx>
Signed-off-by: Bhaumik Bhatt <bbhatt@xxxxxxxxxxxxxx>
---
drivers/bus/mhi/core/boot.c | 15 +++++++--------
drivers/bus/mhi/core/internal.h | 1 +
2 files changed, 8 insertions(+), 8 deletions(-)
diff --git a/drivers/bus/mhi/core/boot.c b/drivers/bus/mhi/core/boot.c
index e5fcde1..9fe9c59 100644
--- a/drivers/bus/mhi/core/boot.c
+++ b/drivers/bus/mhi/core/boot.c
@@ -43,10 +43,7 @@ void mhi_rddm_prepare(struct mhi_controller
*mhi_cntrl,
lower_32_bits(mhi_buf->dma_addr));
mhi_write_reg(mhi_cntrl, base, BHIE_RXVECSIZE_OFFS,
mhi_buf->len);
- sequence_id = prandom_u32() & BHIE_RXVECSTATUS_SEQNUM_BMSK;
-
- if (unlikely(!sequence_id))
- sequence_id = 1;
+ sequence_id = (MHI_RANDOM_U32_NONZERO &
BHIE_RXVECSTATUS_SEQNUM_BMSK);
I don't think this math works. For example, if MHI_RANDOM_U32_NONZERO
is 0x0FF0, and BHIE_RXVECSTATUS_SEQNUM_BMSK is 0xF, then sequence_id
will end up being 0.
In this case, SEQNUM BMSK is set to 0x3FFFFFFF so this change will still
work as
we only supplied a non-zero number macro to AND with the mask.
However, I agree that may not be the case always that we would know the
bitmask
in advance so it is better to fix it for good.
Thanks for the catch! I have updated the change to have the macro take
the
bitmask as a parameter and output a non-zero value.
