net: airoha: Do not read uninitialized fragment address in airoha_dev_xmit()

Overview

In the Linux kernel, the following vulnerability has been resolved:

net: airoha: Do not read uninitialized fragment address in airoha_dev_xmit()

The transmit loop in airoha_dev_xmit() reads fragment address and length during its final iteration, when the loop index equals skb_shinfo(skb)->nr_frags, at which point the fragment data is uninitialized. While these values are never consumed, the read itself is unsafe and may trigger a page fault. Fix this by avoiding the fragment read on the last iteration. Additionally, move the skb pointer from the first to the last used packet descriptor, so that airoha_qdma_tx_napi_poll() defers freeing the skb until the final descriptor is processed.

Affected

• Linux >= 23020f04932701d5c8363e60756f12b43b8ed752 < dba5f4959653e4c212beb746594952e8645d1115
• Linux >= 23020f04932701d5c8363e60756f12b43b8ed752 < f670fa4b19ceddc6d215dda4997888ccba9bbc61
• Linux >= 23020f04932701d5c8363e60756f12b43b8ed752 < d78c8ab7bd84952e053d0c622b7fc1b4ad8a19a3
• Linux >= 23020f04932701d5c8363e60756f12b43b8ed752 < bde34e84edc8b5571fbde7e941e175a4293ee1eb
• Linux 6.11

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.