CVE-2026-98239

Summary

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.

Affected Software

VendorProductVersion RangeStatus
LinuxLinuxcd6910501cfd9a3bdff2f5fc33c9f3cf165ca54a < 0e52886c4324c9897c2c62f92be3dc8316cee67eaffected
LinuxLinuxcd6910501cfd9a3bdff2f5fc33c9f3cf165ca54a < a58024835c704419bb46d2a34e5223f65605f958affected
LinuxLinuxcd6910501cfd9a3bdff2f5fc33c9f3cf165ca54a < 6fe5c3a2503983abb431d93faeadfc7f5e6a7e33affected
LinuxLinuxcd6910501cfd9a3bdff2f5fc33c9f3cf165ca54a < 5c216bfa9fb7b36804485e67975e9c98055b31efaffected
LinuxLinuxcd6910501cfd9a3bdff2f5fc33c9f3cf165ca54a < 161a403c8625e152de03d1da22bbf9cda6dc9f9faffected
LinuxLinuxcd6910501cfd9a3bdff2f5fc33c9f3cf165ca54a < a9ce4053dc945c5372dedba5017ee675b30dc0c5affected
LinuxLinux6.1affected
LinuxLinux0 < 6.1unaffected
LinuxLinux6.1.189 <= 6.1.*unaffected
LinuxLinux6.6.158 <= 6.6.*unaffected
LinuxLinux6.12.112 <= 6.12.*unaffected
LinuxLinux6.18.54 <= 6.18.*unaffected
LinuxLinux7.2.8 <= 7.2.*unaffected
LinuxLinux7.3-rc4 <= *unaffected

Weaknesses

References