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| author | Sumit Kumar <quic_sumk@quicinc.com> | 2025-04-09 16:17:43 +0530 |
|---|---|---|
| committer | Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org> | 2025-04-24 10:34:51 +0530 |
| commit | 6f18d174b73d0ceeaa341f46c0986436b3aefc9a (patch) | |
| tree | a9c6eff39fff61e2a744095346cb6e0623460a8a /drivers/bus | |
| parent | 0af2f6be1b4281385b618cb86ad946eded089ac8 (diff) | |
| download | linux-6f18d174b73d0ceeaa341f46c0986436b3aefc9a.tar.gz linux-6f18d174b73d0ceeaa341f46c0986436b3aefc9a.tar.bz2 linux-6f18d174b73d0ceeaa341f46c0986436b3aefc9a.zip | |
bus: mhi: ep: Update read pointer only after buffer is written
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>
Reviewed-by: Jeff Hugo <jeff.hugo@oss.qualcomm.com>
Reviewed-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://patch.msgid.link/20250409-rp_fix-v1-1-8cf1fa22ed28@quicinc.com
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Diffstat (limited to 'drivers/bus')
| -rw-r--r-- | drivers/bus/mhi/ep/ring.c | 16 |
1 files changed, 10 insertions, 6 deletions
diff --git a/drivers/bus/mhi/ep/ring.c b/drivers/bus/mhi/ep/ring.c index aeb53b2c34a8..26357ee68dee 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) |