On Wed, Apr 09, 2025 at 04:17:43PM +0530, Sumit Kumar wrote:
Inside mhi_ep_ring_add_element, the read pointer (rd_offset) is updated before the buffer is written, potentially causing race conditions where the host sees an updated read pointer before the buffer is actually written. Updating rd_offset prematurely can lead to the host accessing an uninitialized or incomplete element, resulting in data corruption.
Invoke the buffer write before updating rd_offset to ensure the element is fully written before signaling its availability.
Fixes: bbdcba57a1a2 ("bus: mhi: ep: Add support for ring management") cc: stable@vger.kernel.org Co-developed-by: Youssef Samir quic_yabdulra@quicinc.com Signed-off-by: Youssef Samir quic_yabdulra@quicinc.com Signed-off-by: Sumit Kumar quic_sumk@quicinc.com
Applied to mhi-fixes!
- Mani
drivers/bus/mhi/ep/ring.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-)
diff --git a/drivers/bus/mhi/ep/ring.c b/drivers/bus/mhi/ep/ring.c index aeb53b2c34a8cd859393529d0c8860462bc687ed..26357ee68dee984d70ae5bf39f8f09f2cbcafe30 100644 --- a/drivers/bus/mhi/ep/ring.c +++ b/drivers/bus/mhi/ep/ring.c @@ -131,19 +131,23 @@ int mhi_ep_ring_add_element(struct mhi_ep_ring *ring, struct mhi_ring_element *e } old_offset = ring->rd_offset;
- mhi_ep_ring_inc_index(ring);
dev_dbg(dev, "Adding an element to ring at offset (%zu)\n", ring->rd_offset);
- buf_info.host_addr = ring->rbase + (old_offset * sizeof(*el));
- buf_info.dev_addr = el;
- buf_info.size = sizeof(*el);
- ret = mhi_cntrl->write_sync(mhi_cntrl, &buf_info);
- if (ret)
return ret;- mhi_ep_ring_inc_index(ring);
/* Update rp in ring context */ rp = cpu_to_le64(ring->rd_offset * sizeof(*el) + ring->rbase); memcpy_toio((void __iomem *) &ring->ring_ctx->generic.rp, &rp, sizeof(u64));
- buf_info.host_addr = ring->rbase + (old_offset * sizeof(*el));
- buf_info.dev_addr = el;
- buf_info.size = sizeof(*el);
- return mhi_cntrl->write_sync(mhi_cntrl, &buf_info);
- return ret;
} void mhi_ep_ring_init(struct mhi_ep_ring *ring, enum mhi_ep_ring_type type, u32 id)
base-commit: 1e26c5e28ca5821a824e90dd359556f5e9e7b89f change-id: 20250328-rp_fix-d7ebc18bc3be
Best regards,
Sumit Kumar quic_sumk@quicinc.com