sfc: ensure type is valid before updating seen_gen

In the case of invalid or corrupted v2 counter update packets,
 efx_tc_rx_version_2() returns EFX_TC_COUNTER_TYPE_MAX.  In this case
 we should not attempt to update generation counts as this will write
 beyond the end of the seen_gen array.

Reported-by: coverity-bot <keescook+coverity-bot@chromium.org>
Addresses-Coverity-ID: 1527356 ("Memory - illegal accesses")
Fixes: 25730d8be5d8 ("sfc: add extra RX channel to receive MAE counter updates on ef100")
Signed-off-by: Edward Cree <ecree.xilinx@gmail.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/sfc/tc_counters.c b/drivers/net/ethernet/sfc/tc_counters.c
index 2bba5d3..d1a91d5 100644 (file)
--- a/drivers/net/ethernet/sfc/tc_counters.c
+++ b/drivers/net/ethernet/sfc/tc_counters.c
@@ -476,13 +476,15 @@ static bool efx_tc_rx(struct efx_rx_queue *rx_queue, u32 mark)
                goto out;
        }
 
-       /* Update seen_gen unconditionally, to avoid a missed wakeup if
-        * we race with efx_mae_stop_counters().
-        */
-       efx->tc->seen_gen[type] = mark;
-       if (efx->tc->flush_counters &&
-           (s32)(efx->tc->flush_gen[type] - mark) <= 0)
-               wake_up(&efx->tc->flush_wq);
+       if (type < EFX_TC_COUNTER_TYPE_MAX) {
+               /* Update seen_gen unconditionally, to avoid a missed wakeup if
+                * we race with efx_mae_stop_counters().
+                */
+               efx->tc->seen_gen[type] = mark;
+               if (efx->tc->flush_counters &&
+                   (s32)(efx->tc->flush_gen[type] - mark) <= 0)
+                       wake_up(&efx->tc->flush_wq);
+       }
 out:
        efx_free_rx_buffers(rx_queue, rx_buf, 1);
        channel->rx_pkt_n_frags = 0;