net: af_key: initialize alg_key_len for IPComp states

Summary

In the Linux kernel, the following vulnerability has been resolved: net: af_key: initialize alg_key_len for IPComp states pfkey_msg2xfrm_state() handles the IPComp (SADB_X_SATYPE_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->alg_key_len. 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->alg_key_len is later used as a length by xfrm_algo_clone() when an IPComp state is cloned during XFRM_MSG_MIGRATE: xfrm_state_migrate() xfrm_state_clone_and_setup() x->calg = xfrm_algo_clone(orig->calg); kmemdup(orig, xfrm_alg_len(orig)); where xfrm_alg_len() returns sizeof(*alg) + (alg_key_len + 7) / 8. With a non-zero garbage alg_key_len, kmemdup() reads past the end of the 68-byte calg object. Adding an IPComp SA via PF_KEY and then migrating it triggers (net-next, KASAN, init_on_alloc=0): BUG: KASAN: slab-out-of-bounds in kmemdup_noprof+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> dump_stack_lvl+0x10e/0x1f0 print_report+0xf7/0x600 kasan_report+0xe4/0x120 kasan_check_range+0x105/0x1b0 __asan_memcpy+0x23/0x60 kmemdup_noprof+0x44/0x60 xfrm_state_migrate+0x70a/0x1da0 xfrm_migrate+0x753/0x18a0 xfrm_do_migrate+0xb47/0xf10 xfrm_user_rcv_msg+0x411/0xb50 netlink_rcv_skb+0x158/0x420 xfrm_netlink_rcv+0x71/0x90 netlink_unicast+0x584/0x850 netlink_sendmsg+0x8b0/0xdc0 ____sys_sendmsg+0x9f7/0xb90 ___sys_sendmsg+0x134/0x1d0 __sys_sendmsg+0x16d/0x220 do_syscall_64+0x116/0x7d0 entry_SYSCALL_64_after_hwframe+0x77/0x7f </TASK> Allocated by task 9287: kasan_save_stack+0x33/0x60 kasan_save_track+0x14/0x30 __kasan_kmalloc+0xaa/0xb0 pfkey_add+0x2652/0x2ea0 pfkey_process+0x6d0/0x830 pfkey_sendmsg+0x42c/0x850 __sys_sendto+0x461/0x4b0 __x64_sys_sendto+0xe0/0x1c0 do_syscall_64+0x116/0x7d0 entry_SYSCALL_64_after_hwframe+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: verify_one_alg() rejects an XFRMA_ALG_COMP attribute shorter than xfrm_alg_len(), so a calg added via XFRM_MSG_NEWSA is always self-consistent. Initialize calg->alg_key_len to 0, matching the aalg/ealg branches.

Timeline

1. Jul 25, 2026, 8:51 AM UTCCVE published
2. Oct 16, 2026, 3:40 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: partial

3. Oct 19, 2026, 8:38 PM UTCRecord last updated

Affected versions

• Linux Linux

  From 80c9abaabf4283f7cf4a0b3597cd302506635b7f · fixed in 58e82fc3dedb57b1432292504415b224fd2d6acb; From 80c9abaabf4283f7cf4a0b3597cd302506635b7f · fixed in 01b9115b55018123ef2449ac4951f89147a8428e; From 80c9abaabf4283f7cf4a0b3597cd302506635b7f · fixed in 3f63d1752d90c0e28be931a48ab5d89bc97d637d; From 80c9abaabf4283f7cf4a0b3597cd302506635b7f · fixed in 273c06b81d2e902b21acc801ae18c8276c8a9b69; From 80c9abaabf4283f7cf4a0b3597cd302506635b7f · fixed in 6de2a650917bedaaefd65b17cede83c5e2c1dedd; From 80c9abaabf4283f7cf4a0b3597cd302506635b7f · fixed in e8417353cbd078d10531ba3928e609c84ab09e6b; From 80c9abaabf4283f7cf4a0b3597cd302506635b7f · fixed in cea34abc94b0a81e3a8b5cfb41cf45af37c2c67e; From 80c9abaabf4283f7cf4a0b3597cd302506635b7f · fixed in d129c3177d7b1138fd5066fcc63a698b3ba415b0

• Linux Linux

  2.6.21

• KernelLinux

  From 2.6.21 · fixed in 5.10.261; From 5.11.0 · fixed in 5.15.212; From 5.16.0 · fixed in 6.1.178; From 6.2.0 · fixed in 6.6.145; From 6.7.0 · fixed in 6.12.96; From 6.13.0 · fixed in 6.18.39; From 6.19.0 · fixed in 7.1.4

References 8