In the Linux kernel, the following vulnerability has been resolved: mptcp: fix slab-use-after-free in __inet_lookup_established The ehash table lookups are lockless and rely on SLAB_TYPESAFE_BY_RCU to guarantee socket memory stability during RCU read-side critical sections. Both tcp_prot and tcpv6_prot have their slab caches created with this flag via proto_register(). However, MPTCP's mptcp_subflow_init() copies tcpv6_prot into tcpv6_prot_override during inet_init() (fs_initcall, level 5), before inet6_init() (module_init/device_initcall, level 6) has called proto_register(&tcpv6_prot). At that point, tcpv6_prot.slab is still NULL, so tcpv6_prot_override.slab remains NULL permanently. This causes MPTCP v6 subflow child sockets to be allocated via kmalloc (falling into kmalloc-4k) instead of the TCPv6 slab cache. The kmalloc-4k cache lacks SLAB_TYPESAFE_BY_RCU, so when these sockets are freed without SOCK_RCU_FREE (which is cleared for child sockets by design), the memory can be immediately reused. Concurrent ehash lookups under rcu_read_lock can then access freed memory, triggering a slab-use-after-free in __inet_lookup_established. Fix this by splitting the IPv6-specific initialization out of mptcp_subflow_init() into a new mptcp_subflow_v6_init(), called from mptcp_proto_v6_init() before protocol registration. This ensures tcpv6_prot_override.slab correctly inherits the SLAB_TYPESAFE_BY_RCU slab cache.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
| Attack Vector | NETWORK |
|---|---|
| Attack Complexity | LOW |
| Privileges Required | NONE |
| User Interaction | NONE |
| Scope | UNCHANGED |
| Confidentiality Impact | HIGH |
| Integrity Impact | HIGH |
| Availability Impact | HIGH |
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Type: Secondary
Exploitability Score: 3.9
Impact Score: 5.9
| Source | Type | Description |
|---|---|---|
| [email protected] | Primary |
en
CWE-416
|
| Vendor | Product | Version | Update | Type |
|---|---|---|---|---|
| linux | linux_kernel | * | <built-in method update of dict object at 0x702b51b5ad00> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x702b51b58ec0> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x702bdcf6b780> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x702b4032b800> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x702b51b59840> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x702b51b59340> | Operating System |
| linux | linux_kernel | 5.12 | <built-in method update of dict object at 0x702bddf539c0> | Operating System |
| linux | linux_kernel | 7.0 | <built-in method update of dict object at 0x702bdcf68280> | Operating System |
| linux | linux_kernel | 7.0 | <built-in method update of dict object at 0x702c04583680> | Operating System |
| linux | linux_kernel | 7.0 | <built-in method update of dict object at 0x702b51b5a9c0> | Operating System |
| linux | linux_kernel | 7.0 | <built-in method update of dict object at 0x702b4032b200> | Operating System |
| linux | linux_kernel | 7.0 | <built-in method update of dict object at 0x702b4032b040> | Operating System |
| linux | linux_kernel | 7.0 | <built-in method update of dict object at 0x702bdcf694c0> | Operating System |
| linux | linux_kernel | 7.0 | <built-in method update of dict object at 0x702bddf52900> | Operating System |
| Vulnerable | CPE |
|---|---|
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:5.12:-:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:7.0:rc6:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:7.0:rc7:*:*:*:*:*:* |