bus: mhi: host: Add alignment check for event ring read pointer

commit eff9704f5332a13b08fbdbe0f84059c9e7051d5f upstream.

Though we do check the event ring read pointer by "is_valid_ring_ptr"
to make sure it is in the buffer range, but there is another risk the
pointer may be not aligned.  Since we are expecting event ring elements
are 128 bits(struct mhi_ring_element) aligned, an unaligned read pointer
could lead to multiple issues like DoS or ring buffer memory corruption.

So add a alignment check for event ring read pointer.

Fixes: ec32332df764 ("bus: mhi: core: Sanity check values from remote device before use")
cc: stable@vger.kernel.org
Signed-off-by: Krishna chaitanya chundru <quic_krichai@quicinc.com>
Reviewed-by: Jeffrey Hugo <quic_jhugo@quicinc.com>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/20231031-alignment_check-v2-1-1441db7c5efd@quicinc.com
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/bus/mhi/host/main.c b/drivers/bus/mhi/host/main.c
index dcf627b..3a6ccab 100644 (file)
--- a/drivers/bus/mhi/host/main.c
+++ b/drivers/bus/mhi/host/main.c
@@ -268,7 +268,8 @@ static void mhi_del_ring_element(struct mhi_controller *mhi_cntrl,
 
 static bool is_valid_ring_ptr(struct mhi_ring *ring, dma_addr_t addr)
 {
-       return addr >= ring->iommu_base && addr < ring->iommu_base + ring->len;
+       return addr >= ring->iommu_base && addr < ring->iommu_base + ring->len &&
+                       !(addr & (sizeof(struct mhi_ring_element) - 1));
 }
 
 int mhi_destroy_device(struct device *dev, void *data)