Linux Kernel GMAC Fragment Counter Reset State Loss
CVE-2026-64055 Published on July 19, 2026
net: ethernet: cortina: Carry over frag counter
In the Linux kernel, the following vulnerability has been resolved:
net: ethernet: cortina: Carry over frag counter
The gmac_rx() NAPI poll function assembles packets in an
SKB from a ring buffer.
If the ring buffer gets completely emptied during a poll cycle,
we exit gmac_rx(), but the packet is not yet completely
assembled in the SKB, yet the fragment counter frag_nr is
reset to zero on the next invocation.
Solve this by making the RX fragment counter a part of the
port struct, and carry it over between invocations.
Reset the fragment counter only right after calling
napi_gro_frags(), on error (after calling napi_free_frags())
or if stopping the port.
Reset it in some place where not strictly necessary just to
emphasize what is going on.
This was found by Sashiko during normal patch review.
Products Associated with CVE-2026-64055
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Affected Versions
Linux:- Version 4d5ae32f5e1e13f7f36d6439ec3257993b9f5b88 and below df31e3b64455293df1ea89c7da7d5c9bfbcdd253 is affected.
- Version 4d5ae32f5e1e13f7f36d6439ec3257993b9f5b88 and below 7af1fabdee744b7995fe01b30b77dfc397657cb5 is affected.
- Version 4d5ae32f5e1e13f7f36d6439ec3257993b9f5b88 and below 75105fcf73f1ce7d9f769aaefec6e6d6645d5ac0 is affected.
- Version 4d5ae32f5e1e13f7f36d6439ec3257993b9f5b88 and below 78cf08b3be47c28f07008a76c932bad7cdffa9d8 is affected.
- Version 4d5ae32f5e1e13f7f36d6439ec3257993b9f5b88 and below 7123cf481e21b54eb6adc4cb0d8dc2876aeaee41 is affected.
- Version 4d5ae32f5e1e13f7f36d6439ec3257993b9f5b88 and below c373b34877afea61c89e0dd2e38948c624249b9b is affected.
- Version 4d5ae32f5e1e13f7f36d6439ec3257993b9f5b88 and below 46806096f35b8d3dfa2f321ddd77f597edcdb85f is affected.
- Version 4d5ae32f5e1e13f7f36d6439ec3257993b9f5b88 and below ebd8ec2b309e3a447851b456ccaf8fb39f3661e7 is affected.
- Version 4.16 is affected.
- Before 4.16 is unaffected.
- Version 5.10.258, <= 5.10.* is unaffected.
- Version 5.15.209, <= 5.15.* is unaffected.
- Version 6.1.175, <= 6.1.* is unaffected.
- Version 6.6.142, <= 6.6.* is unaffected.
- Version 6.12.92, <= 6.12.* is unaffected.
- Version 6.18.34, <= 6.18.* is unaffected.
- Version 7.0.11, <= 7.0.* is unaffected.
- Version 7.1, <= * is unaffected.