net: amd-xgbe: Fix skb data length underflow

commit 5aac9108a180fc06e28d4e7fb00247ce603b72ee upstream.

There will be BUG_ON() triggered in include/linux/skbuff.h leading to
intermittent kernel panic, when the skb length underflow is detected.

Fix this by dropping the packet if such length underflows are seen
because of inconsistencies in the hardware descriptors.

Fixes: 622c36f143fc ("amd-xgbe: Fix jumbo MTU processing on newer hardware")
Suggested-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
Acked-by: Tom Lendacky <thomas.lendacky@amd.com>
Link: https://lore.kernel.org/r/20220127092003.2812745-1-Shyam-sundar.S-k@amd.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-drv.c b/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
index 4c515a497a2ba899fc943edfd0dd4db0fa9798e8..e6883d52d230c8901bf1d3d474ec63dc42884c3a 100644 (file)
--- a/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
+++ b/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
@@ -2557,6 +2557,14 @@ read_again:
                        buf2_len = xgbe_rx_buf2_len(rdata, packet, len);
                        len += buf2_len;
 
+                       if (buf2_len > rdata->rx.buf.dma_len) {
+                               /* Hardware inconsistency within the descriptors
+                                * that has resulted in a length underflow.
+                                */
+                               error = 1;
+                               goto skip_data;
+                       }
+
                        if (!skb) {
                                skb = xgbe_create_skb(pdata, napi, rdata,
                                                      buf1_len);
@@ -2586,8 +2594,10 @@ skip_data:
                if (!last || context_next)
                        goto read_again;
 
-               if (!skb)
+               if (!skb || error) {
+                       dev_kfree_skb(skb);
                        goto next_packet;
+               }
 
                /* Be sure we don't exceed the configured MTU */
                max_len = netdev->mtu + ETH_HLEN;