CVE-2026-98239
Description
In the Linux kernel, the following vulnerability has been resolved: net: lan743x: fix RX checksum use-after-free lan743x_rx_process_buffer() adds each non-first receive buffer to the head skb's frag_list. On the last descriptor, lan743x_rx_trim_skb() linearizes the head and frees the fragment skb metadata. The checksum-success path then writes ip_summed through the local skb pointer, which still points to the final fragment. This causes a use-after-free write when a packet spans more than one receive buffer. Set ip_summed on the surviving head skb instead. Multi-buffer receive can occur after a live MTU increase because existing ring entries keep their old buffer size until they are replenished. A KUnit test invoking lan743x_rx_process_buffer() with a two-buffer packet produced a one-byte KASAN use-after-free write before this change. The same test passed after the change. The driver object also builds with W=1. This was not tested on physical LAN743x hardware.
How to fix
- Linux Linux0e52886c4324c9897c2c62f92be3dc8316cee67e, a58024835c704419bb46d2a34e5223f65605f958, 6fe5c3a2503983abb431d93faeadfc7f5e6a7e33, 5c216bfa9fb7b36804485e67975e9c98055b31ef, 161a403c8625e152de03d1da22bbf9cda6dc9f9f, a9ce4053dc945c5372dedba5017ee675b30dc0c5 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| Linux Linux | cd6910501cfd9a3bdff2f5fc33c9f3cf165ca54a ≤ v < 0e52886c4324c9897c2c62f92be3dc8316cee67e, cd6910501cfd9a3bdff2f5fc33c9f3cf165ca54a ≤ v < a58024835c704419bb46d2a34e5223f65605f958, cd6910501cfd9a3bdff2f5fc33c9f3cf165ca54a ≤ v < 6fe5c3a2503983abb431d93faeadfc7f5e6a7e33, cd6910501cfd9a3bdff2f5fc33c9f3cf165ca54a ≤ v < 5c216bfa9fb7b36804485e67975e9c98055b31ef, cd6910501cfd9a3bdff2f5fc33c9f3cf165ca54a ≤ v < 161a403c8625e152de03d1da22bbf9cda6dc9f9f, cd6910501cfd9a3bdff2f5fc33c9f3cf165ca54a ≤ v < a9ce4053dc945c5372dedba5017ee675b30dc0c5, 6.1 | 0e52886c4324c9897c2c62f92be3dc8316cee67e, a58024835c704419bb46d2a34e5223f65605f958, 6fe5c3a2503983abb431d93faeadfc7f5e6a7e33, 5c216bfa9fb7b36804485e67975e9c98055b31ef, 161a403c8625e152de03d1da22bbf9cda6dc9f9f, a9ce4053dc945c5372dedba5017ee675b30dc0c5 |
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