CVE-2025-38052

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

net/tipc: fix slab-use-after-free Read in tipc_aead_encrypt_done

Syzbot reported a slab-use-after-free with the following call trace:

==================================================================

BUG: KASAN: slab-use-after-free in tipc_aead_encrypt_done+0x4bd/0x510 net/tipc/crypto.c:840

Read of size 8 at addr ffff88807a733000 by task kworker/1:0/25

Call Trace:

kasan_report+0xd9/0x110 mm/kasan/report.c:601

tipc_aead_encrypt_done+0x4bd/0x510 net/tipc/crypto.c:840

crypto_request_complete include/crypto/algapi.h:266

aead_request_complete include/crypto/internal/aead.h:85

cryptd_aead_crypt+0x3b8/0x750 crypto/cryptd.c:772

crypto_request_complete include/crypto/algapi.h:266

cryptd_queue_worker+0x131/0x200 crypto/cryptd.c:181

process_one_work+0x9fb/0x1b60 kernel/workqueue.c:3231

Allocated by task 8355:

kzalloc_noprof include/linux/slab.h:778

tipc_crypto_start+0xcc/0x9e0 net/tipc/crypto.c:1466

tipc_init_net+0x2dd/0x430 net/tipc/core.c:72

ops_init+0xb9/0x650 net/core/net_namespace.c:139

setup_net+0x435/0xb40 net/core/net_namespace.c:343

copy_net_ns+0x2f0/0x670 net/core/net_namespace.c:508

create_new_namespaces+0x3ea/0xb10 kernel/nsproxy.c:110

unshare_nsproxy_namespaces+0xc0/0x1f0 kernel/nsproxy.c:228

ksys_unshare+0x419/0x970 kernel/fork.c:3323

__do_sys_unshare kernel/fork.c:3394

Freed by task 63:

kfree+0x12a/0x3b0 mm/slub.c:4557

tipc_crypto_stop+0x23c/0x500 net/tipc/crypto.c:1539

tipc_exit_net+0x8c/0x110 net/tipc/core.c:119

ops_exit_list+0xb0/0x180 net/core/net_namespace.c:173

cleanup_net+0x5b7/0xbf0 net/core/net_namespace.c:640

process_one_work+0x9fb/0x1b60 kernel/workqueue.c:3231

After freed the tipc_crypto tx by delete namespace, tipc_aead_encrypt_done

may still visit it in cryptd_queue_worker workqueue.

I reproduce this issue by:

ip netns add ns1

ip link add veth1 type veth peer name veth2

ip link set veth1 netns ns1

ip netns exec ns1 tipc bearer enable media eth dev veth1

ip netns exec ns1 tipc node set key this_is_a_master_key master

ip netns exec ns1 tipc bearer disable media eth dev veth1

ip netns del ns1

The key of reproduction is that, simd_aead_encrypt is interrupted, leading

to crypto_simd_usable() return false. Thus, the cryptd_queue_worker is

triggered, and the tipc_crypto tx will be visited.

tipc_disc_timeout

tipc_bearer_xmit_skb

tipc_crypto_xmit

tipc_aead_encrypt

crypto_aead_encrypt

// encrypt()

simd_aead_encrypt

// crypto_simd_usable() is false

child = &ctx->cryptd_tfm->base;

simd_aead_encrypt

crypto_aead_encrypt

// encrypt()

cryptd_aead_encrypt_enqueue

cryptd_aead_enqueue

cryptd_enqueue_request

// trigger cryptd_queue_worker

queue_work_on(smp_processor_id(), cryptd_wq, &cpu_queue->work)

Fix this by holding net reference count before encrypt.