fix double-free of tx_buf skb

Summary

In the Linux kernel, the following vulnerability has been resolved: 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. A flaw was found in the Linux kernel's ice network driver. An error in the driver's handling of network packet transmission, specifically when ice_tso() or ice_tx_csum() functions fail, can lead to a double-free of a network buffer (skb). This occurs because a transmit buffer (tx_buf) may still point to an already freed buffer. If the network interface is subsequently brought down, this double-free can be triggered, potentially leading to a system crash or denial of service (DoS). Red Hat severity: Important — CVSS 7 (CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H). Weakness: CWE-1341. No fixing RHSA erratum has published yet; monitor the Red Hat CVE page and patch when it ships.