CVE-2026-64048

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

net/smc: reject CHID-0 ACCEPT that matches an empty ism_dev slot

On the SMC-D client, slot 0 of ini->ism_dev[]/ini->ism_chid[] is

reserved for an SMC-Dv1 device. smc_find_ism_v2_device_clnt()

populates V2 entries starting at index 1, so when no V1 device is

selected slot 0 is left in its kzalloc()'ed state with ism_dev[0] ==

NULL and ism_chid[0] == 0.

smc_v2_determine_accepted_chid() then matches the peer's CHID against

the array starting from index 0 using the CHID alone. A malicious

peer replying to a SMC-Dv2-only proposal with d1.chid == 0 matches

the empty slot, ini->ism_selected becomes 0, and the subsequent

ism_dev[0]->lgr_lock dereference in smc_conn_create() faults at

offsetof(struct smcd_dev, lgr_lock) == 0x68:

BUG: KASAN: null-ptr-deref in _raw_spin_lock_bh+0x79/0xe0

Write of size 4 at addr 0000000000000068 by task exploit/144

Call Trace:

_raw_spin_lock_bh

smc_conn_create (net/smc/smc_core.c:1997)

__smc_connect (net/smc/af_smc.c:1447)

smc_connect (net/smc/af_smc.c:1720)

__sys_connect

__x64_sys_connect

do_syscall_64

Require ism_dev[i] to be non-NULL before accepting a CHID match.