ath10k: sanitize tx ring index access properly

The tx ring index was immediately trimmed with a
bitmask. This discarded the 0xFFFFFFFF error case
(which theoretically can happen when a device is
abruptly disconnected) and led to using an invalid
tx ring index. This could lead to memory
corruption.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

diff --git a/drivers/net/wireless/ath/ath10k/ce.c b/drivers/net/wireless/ath/ath10k/ce.c
index d185dc0..4333107 100644 (file)
--- a/drivers/net/wireless/ath/ath10k/ce.c
+++ b/drivers/net/wireless/ath/ath10k/ce.c
@@ -603,16 +603,19 @@ static int ath10k_ce_completed_send_next_nolock(struct ath10k_ce_pipe *ce_state,
                if (ret)
                        return ret;
 
-               src_ring->hw_index =
-                       ath10k_ce_src_ring_read_index_get(ar, ctrl_addr);
-               src_ring->hw_index &= nentries_mask;
+               read_index = ath10k_ce_src_ring_read_index_get(ar, ctrl_addr);
+               if (read_index == 0xffffffff)
+                       return -ENODEV;
+
+               read_index &= nentries_mask;
+               src_ring->hw_index = read_index;
 
                ath10k_pci_sleep(ar);
        }
 
        read_index = src_ring->hw_index;
 
-       if ((read_index == sw_index) || (read_index == 0xffffffff))
+       if (read_index == sw_index)
                return -EIO;
 
        sbase = src_ring->shadow_base;