CVE-2026-64055: net: ethernet: cortina: Carry over frag counter

From: Greg Kroah-Hartman <[email protected]>

Description
===========

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.

The Linux kernel CVE team has assigned CVE-2026-64055 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 4.16 with commit 4d5ae32f5e1e13f7f36d6439ec3257993b9f5b88 and fixed in 5.10.258 with commit df31e3b64455293df1ea89c7da7d5c9bfbcdd253
	Issue introduced in 4.16 with commit 4d5ae32f5e1e13f7f36d6439ec3257993b9f5b88 and fixed in 5.15.209 with commit 7af1fabdee744b7995fe01b30b77dfc397657cb5
	Issue introduced in 4.16 with commit 4d5ae32f5e1e13f7f36d6439ec3257993b9f5b88 and fixed in 6.1.175 with commit 75105fcf73f1ce7d9f769aaefec6e6d6645d5ac0
	Issue introduced in 4.16 with commit 4d5ae32f5e1e13f7f36d6439ec3257993b9f5b88 and fixed in 6.6.142 with commit 78cf08b3be47c28f07008a76c932bad7cdffa9d8
	Issue introduced in 4.16 with commit 4d5ae32f5e1e13f7f36d6439ec3257993b9f5b88 and fixed in 6.12.92 with commit 7123cf481e21b54eb6adc4cb0d8dc2876aeaee41
	Issue introduced in 4.16 with commit 4d5ae32f5e1e13f7f36d6439ec3257993b9f5b88 and fixed in 6.18.34 with commit c373b34877afea61c89e0dd2e38948c624249b9b
	Issue introduced in 4.16 with commit 4d5ae32f5e1e13f7f36d6439ec3257993b9f5b88 and fixed in 7.0.11 with commit 46806096f35b8d3dfa2f321ddd77f597edcdb85f
	Issue introduced in 4.16 with commit 4d5ae32f5e1e13f7f36d6439ec3257993b9f5b88 and fixed in 7.1 with commit ebd8ec2b309e3a447851b456ccaf8fb39f3661e7

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2026-64055
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	drivers/net/ethernet/cortina/gemini.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/df31e3b64455293df1ea89c7da7d5c9bfbcdd253
	https://git.kernel.org/stable/c/7af1fabdee744b7995fe01b30b77dfc397657cb5
	https://git.kernel.org/stable/c/75105fcf73f1ce7d9f769aaefec6e6d6645d5ac0
	https://git.kernel.org/stable/c/78cf08b3be47c28f07008a76c932bad7cdffa9d8
	https://git.kernel.org/stable/c/7123cf481e21b54eb6adc4cb0d8dc2876aeaee41
	https://git.kernel.org/stable/c/c373b34877afea61c89e0dd2e38948c624249b9b
	https://git.kernel.org/stable/c/46806096f35b8d3dfa2f321ddd77f597edcdb85f
	https://git.kernel.org/stable/c/ebd8ec2b309e3a447851b456ccaf8fb39f3661e7