CVE-2024-56717: net: mscc: ocelot: fix incorrect IFH SRC_PORT field in ocelot_ifh_set_basic()

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-12-29 · updated 2026-08-04

Description

In the Linux kernel, the following vulnerability has been resolved: net: mscc: ocelot: fix incorrect IFH SRC_PORT field in ocelot_ifh_set_basic() Packets injected by the CPU should have a SRC_PORT field equal to the CPU port module index in the Analyzer block (ocelot->num_phys_ports). The blamed commit copied the ocelot_ifh_set_basic() call incorrectly from ocelot_xmit_common() in net/dsa/tag_ocelot.c. Instead of calling with "x", it calls with BIT_ULL(x), but the field is not a port mask, but rather a single port index. [ side note: this is the technical debt of code duplication :( ] The error used to be silent and doesn't appear to have other user-visible manifestations, but with new changes in the packing library, it now fails loudly as follows: ------------[ cut here ]------------ Cannot store 0x40 inside bits 46-43 - will truncate sja1105 spi2.0: xmit timed out WARNING: CPU: 1 PID: 102 at lib/packing.c:98 __pack+0x90/0x198 sja1105 spi2.0: timed out polling for tstamp CPU: 1 UID: 0 PID: 102 Comm: felix_xmit Tainted: G W N 6.13.0-rc1-00372-gf706b85d972d-dirty #2605 Call trace: __pack+0x90/0x198 (P) __pack+0x90/0x198 (L) packing+0x78/0x98 ocelot_ifh_set_basic+0x260/0x368 ocelot_port_inject_frame+0xa8/0x250 felix_port_deferred_xmit+0x14c/0x258 kthread_worker_fn+0x134/0x350 kthread+0x114/0x138 The code path pertains to the ocelot switchdev driver and to the felix secondary DSA tag protocol, ocelot-8021q. Here seen with ocelot-8021q. The messenger (packing) is not really to blame, so fix the original commit instead.

Affected products

Linux kernel: from 6.1.107 before 6.1.122; from 6.6.48 before 6.6.68; from 6.10.7 before 6.12.7; 6.13-rc1, 6.13-rc2, 6.13-rc3 — fixed in 6.1.122, 6.12.7, 6.6.68

How to fix

Upgrade to a fixed version: Linux kernel 6.1.122, 6.12.7, 6.6.68. Check the vendor advisory for mitigations.

References

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