CVE-2026-64436

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

net: afkey: initialize algkey_len for IPComp states

pfkeymsg2xfrmstate() handles the IPComp (SADBXSATYPE_IPCOMP) case by allocating x->calg and copying only the algorithm name:

x->calg = kmalloc_obj(*x->calg);
if (!x->calg) {
    err = -ENOMEM;
    goto out;
}
strcpy(x->calg->alg_name, a->name);
x->props.calgo = sa->sadb_sa_encrypt;

Unlike the authentication (x->aalg) and encryption (x->ealg) branches of the same function, the compression branch never initializes calg->algkeylen. IPComp carries no key and the allocation only reserves sizeof(struct xfrm_algo) (i.e. no room for a key), so the field is left containing uninitialized slab data.

calg->algkeylen is later used as a length by xfrmalgoclone() when an IPComp state is cloned during XFRMMSGMIGRATE:

xfrm_state_migrate()
  xfrm_state_clone_and_setup()
    x->calg = xfrm_algo_clone(orig->calg);
      kmemdup(orig, xfrm_alg_len(orig));

where xfrmalglen() returns sizeof(*alg) + (algkeylen + 7) / 8. With a non-zero garbage algkeylen, kmemdup() reads past the end of the 68-byte calg object. Adding an IPComp SA via PFKEY and then migrating it triggers (net-next, KASAN, initon_alloc=0):

BUG: KASAN: slab-out-of-bounds in kmemdupnoprof+0x44/0x60 Read of size 4164 at addr ff11000025a74980 by task diag2/9287 CPU: 3 UID: 0 PID: 9287 Comm: diag2 7.1.0-rc6-g903db046d557 #1 Call Trace: <TASK> dumpstacklvl+0x10e/0x1f0 printreport+0xf7/0x600 kasanreport+0xe4/0x120 kasancheck_range+0x105/0x1b0 __asanmemcpy+0x23/0x60 kmemdupnoprof+0x44/0x60 xfrmstatemigrate+0x70a/0x1da0 xfrmmigrate+0x753/0x18a0 xfrmdomigrate+0xb47/0xf10 xfrmuserrcvmsg+0x411/0xb50 netlinkrcvskb+0x158/0x420 xfrmnetlinkrcv+0x71/0x90 netlinkunicast+0x584/0x850 netlinksendmsg+0x8b0/0xdc0 ____sys_sendmsg+0x9f7/0xb90 ___sys_sendmsg+0x134/0x1d0 _syssendmsg+0x16d/0x220 dosyscall64+0x116/0x7d0 entrySYSCALL64afterhwframe+0x77/0x7f </TASK>

Allocated by task 9287: kasansavestack+0x33/0x60 kasansavetrack+0x14/0x30 __kasankmalloc+0xaa/0xb0 pfkeyadd+0x2652/0x2ea0 pfkeyprocess+0x6d0/0x830 pfkeysendmsg+0x42c/0x850 __sys_sendto+0x461/0x4b0 __x64syssendto+0xe0/0x1c0 dosyscall64+0x116/0x7d0 entrySYSCALL64afterhwframe+0x77/0x7f

The buggy address belongs to the object at ff11000025a74980 which belongs to the cache kmalloc-96 of size 96 The buggy address is located 0 bytes inside of allocated 68-byte region [ff11000025a74980, ff11000025a749c4)

Depending on the uninitialized value the same field can instead request an oversized kmemdup() allocation and make the migration clone fail.

The XFRM netlink path is not affected: verifyonealg() rejects an XFRMAALGCOMP attribute shorter than xfrmalglen(), so a calg added via XFRMMSGNEWSA is always self-consistent.

Initialize calg->algkeylen to 0, matching the aalg/ealg branches.