CVE-2026-43036 PUBLISHED

net: use skb_header_pointer() for TCPv4 GSO frag_off check

Assigner: Linux
Reserved: 01.05.2026 Published: 01.05.2026 Updated: 01.05.2026

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

net: use skb_header_pointer() for TCPv4 GSO frag_off check

Syzbot reported a KMSAN uninit-value warning in gso_features_check() called from netif_skb_features() [1].

gso_features_check() reads iph->frag_off to decide whether to clear mangleid_features. Accessing the IPv4 header via ip_hdr()/inner_ip_hdr() can rely on skb header offsets that are not always safe for direct dereference on packets injected from PF_PACKET paths.

Use skb_header_pointer() for the TCPv4 frag_off check so the header read is robust whether data is already linear or needs copying.

[1] https://syzkaller.appspot.com/bug?extid=1543a7d954d9c6d00407

Product Status

Vendor Linux
Product Linux
Versions Default: unaffected
  • affected from cbc53e08a793b073e79f42ca33f1f3568703540d to f7a6cd508e9e825a2c69fa9e13d41ee156852f25 (excl.)
  • affected from cbc53e08a793b073e79f42ca33f1f3568703540d to cc91202fc20a44aab4c206f12a2bfe05da936051 (excl.)
  • affected from cbc53e08a793b073e79f42ca33f1f3568703540d to d970341cfa5594614c7a6634886c7688b4f5cafd (excl.)
  • affected from cbc53e08a793b073e79f42ca33f1f3568703540d to ddc748a391dd8642ba6b2e4fe22e7f2ddf84b7f0 (excl.)
Vendor Linux
Product Linux
Versions Default: affected
  • Version 4.7 is affected
  • unaffected from 0 to 4.7 (excl.)
  • unaffected from 6.12.81 to 6.12.* (incl.)
  • unaffected from 6.18.22 to 6.18.* (incl.)
  • unaffected from 6.19.12 to 6.19.* (incl.)
  • unaffected from 7.0 to * (incl.)

References