ice: fix double-free of tx_buf skb

If ice_tso() or ice_tx_csum() fail, the error path in
ice_xmit_frame_ring() frees the skb, but the 'first' tx_buf still points
to it and is marked as valid (ICE_TX_BUF_SKB).
'next_to_use' remains unchanged, so the potential problem will
likely fix itself when the next packet is transmitted and the tx_buf
gets overwritten. But if there is no next packet and the interface is
brought down instead, ice_clean_tx_ring() -> ice_unmap_and_free_tx_buf()
will find the tx_buf and free the skb for the second time.

The fix is to reset the tx_buf type to ICE_TX_BUF_EMPTY in the error
path, so that ice_unmap_and_free_tx_buf().
Move the initialization of 'first' up, to ensure it's already valid in
case we hit the linearization error path.

The bug was spotted by AI while I had it looking for something else.
It also proposed an initial version of the patch.

I reproduced the bug and tested the fix by adding code to inject
failures, on a build with KASAN.

I looked for similar bugs in related Intel drivers and did not find any.

Fixes: d76a60ba7afb ("ice: Add support for VLANs and offloads")
Assisted-by: Claude:claude-4.6-opus-high Cursor
Signed-off-by: Michal Schmidt <mschmidt@redhat.com>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://patch.msgid.link/20260416-iwl-net-submission-2026-04-14-v2-4-686c33c9828d@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/ethernet/intel/ice/ice_txrx.c b/drivers/net/ethernet/intel/ice/ice_txrx.c
index a2cd4cf37734820a895cdecf6ab75f907ea4985d..7be9c062949b82c365e53096b867c9711ca63ccb 100644 (file)
--- a/drivers/net/ethernet/intel/ice/ice_txrx.c
+++ b/drivers/net/ethernet/intel/ice/ice_txrx.c
@@ -2158,6 +2158,9 @@ ice_xmit_frame_ring(struct sk_buff *skb, struct ice_tx_ring *tx_ring)
 
        ice_trace(xmit_frame_ring, tx_ring, skb);
 
+       /* record the location of the first descriptor for this packet */
+       first = &tx_ring->tx_buf[tx_ring->next_to_use];
+
        count = ice_xmit_desc_count(skb);
        if (ice_chk_linearize(skb, count)) {
                if (__skb_linearize(skb))
@@ -2183,8 +2186,6 @@ ice_xmit_frame_ring(struct sk_buff *skb, struct ice_tx_ring *tx_ring)
 
        offload.tx_ring = tx_ring;
 
-       /* record the location of the first descriptor for this packet */
-       first = &tx_ring->tx_buf[tx_ring->next_to_use];
        first->skb = skb;
        first->type = ICE_TX_BUF_SKB;
        first->bytecount = max_t(unsigned int, skb->len, ETH_ZLEN);
@@ -2249,6 +2250,7 @@ ice_xmit_frame_ring(struct sk_buff *skb, struct ice_tx_ring *tx_ring)
 out_drop:
        ice_trace(xmit_frame_ring_drop, tx_ring, skb);
        dev_kfree_skb_any(skb);
+       first->type = ICE_TX_BUF_EMPTY;
        return NETDEV_TX_OK;
 }