CVE-2024-56717

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.