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 933ccae14f976bd2adbde2a52ed91571e162e260..78412d6024aad68b93300326fc4682ba411feffe 100644 (file)
--- a/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
+++ b/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
@@ -2722,6 +2722,14 @@ 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);
@@ -2751,8 +2759,10 @@ 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;