[PATCH 5.10] bus: mhi: host: Add alignment check for event ring read pointer

From: Krishna chaitanya chundru <[email protected]>

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: [email protected]
Signed-off-by: Krishna chaitanya chundru <[email protected]>
Reviewed-by: Jeffrey Hugo <[email protected]>
Reviewed-by: Manivannan Sadhasivam <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Manivannan Sadhasivam <[email protected]>
Signed-off-by: Alexander Martyniuk <[email protected]>
---
Backport fix for CVE-2023-52494
 drivers/bus/mhi/host/main.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/bus/mhi/host/main.c b/drivers/bus/mhi/host/main.c
index 49c0f5ad0b73..57c8d15b687c 100644
--- a/drivers/bus/mhi/host/main.c
+++ b/drivers/bus/mhi/host/main.c
@@ -222,7 +222,8 @@ 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_tre) - 1));
 }
 
 int mhi_destroy_device(struct device *dev, void *data)
-- 
2.47.3