阿里云漏洞库

漏洞描述

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

sctp: use call_rcu to free endpoint

This patch is to delay the endpoint free by calling call_rcu() to fix

another use-after-free issue in sctp_sock_dump():

BUG: KASAN: use-after-free in __lock_acquire+0x36d9/0x4c20

Call Trace:

__lock_acquire+0x36d9/0x4c20 kernel/locking/lockdep.c:3218

lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3844

__raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline]

_raw_spin_lock_bh+0x31/0x40 kernel/locking/spinlock.c:168

spin_lock_bh include/linux/spinlock.h:334 [inline]

__lock_sock+0x203/0x350 net/core/sock.c:2253

lock_sock_nested+0xfe/0x120 net/core/sock.c:2774

lock_sock include/net/sock.h:1492 [inline]

sctp_sock_dump+0x122/0xb20 net/sctp/diag.c:324

sctp_for_each_transport+0x2b5/0x370 net/sctp/socket.c:5091

sctp_diag_dump+0x3ac/0x660 net/sctp/diag.c:527

__inet_diag_dump+0xa8/0x140 net/ipv4/inet_diag.c:1049

inet_diag_dump+0x9b/0x110 net/ipv4/inet_diag.c:1065

netlink_dump+0x606/0x1080 net/netlink/af_netlink.c:2244

__netlink_dump_start+0x59a/0x7c0 net/netlink/af_netlink.c:2352

netlink_dump_start include/linux/netlink.h:216 [inline]

inet_diag_handler_cmd+0x2ce/0x3f0 net/ipv4/inet_diag.c:1170

__sock_diag_cmd net/core/sock_diag.c:232 [inline]

sock_diag_rcv_msg+0x31d/0x410 net/core/sock_diag.c:263

netlink_rcv_skb+0x172/0x440 net/netlink/af_netlink.c:2477

sock_diag_rcv+0x2a/0x40 net/core/sock_diag.c:274

This issue occurs when asoc is peeled off and the old sk is freed after

getting it by asoc->base.sk and before calling lock_sock(sk).

To prevent the sk free, as a holder of the sk, ep should be alive when

calling lock_sock(). This patch uses call_rcu() and moves sock_put and

ep free into sctp_endpoint_destroy_rcu(), so that it's safe to try to

hold the ep under rcu_read_lock in sctp_transport_traverse_process().

If sctp_endpoint_hold() returns true, it means this ep is still alive

and we have held it and can continue to dump it; If it returns false,

it means this ep is dead and can be freed after rcu_read_unlock, and

we should skip it.

In sctp_sock_dump(), after locking the sk, if this ep is different from

tsp->asoc->ep, it means during this dumping, this asoc was peeled off

before calling lock_sock(), and the sk should be skipped; If this ep is

the same with tsp->asoc->ep, it means no peeloff happens on this asoc,

and due to lock_sock, no peeloff will happen either until release_sock.

Note that delaying endpoint free won't delay the port release, as the

port release happens in sctp_endpoint_destroy() before calling call_rcu().

Also, freeing endpoint by call_rcu() makes it safe to access the sk by

asoc->base.sk in sctp_assocs_seq_show() and sctp_rcv().

Thanks Jones to bring this issue up.

v1->v2:

- improve the changelog.

- add kfree(ep) into sctp_endpoint_destroy_rcu(), as Jakub noticed.

解决建议

建议您更新当前系统或软件至最新版，完成漏洞的修复。

参考链接
https://git.kernel.org/stable/c/5ec7d18d1813a5bead0b495045606c93873aecbb
https://git.kernel.org/stable/c/75799e71df1da11394740b43ae5686646179561d
https://git.kernel.org/stable/c/769d14abd35e0e153b5149c3e1e989a9d719e3ff
https://git.kernel.org/stable/c/831de271452b87657fcf8d715ee20519b79caef5
https://git.kernel.org/stable/c/8873140f95d4977bf37e4cf0d5c5e3f6e34cdd3e
https://git.kernel.org/stable/c/af6e6e58f7ebf86b4e7201694b1e4f3a62cbc3ec

受影响软件情况

1
#	类型	厂商	产品	版本	影响面
	运行在以下环境
	系统	debian_10	linux	*		Up to (excluding) 4.19.232-1
	运行在以下环境
	系统	debian_11	linux	*		Up to (excluding) 5.10.92-1
	运行在以下环境
	系统	debian_12	linux	*		Up to (excluding) 5.15.15-1
	运行在以下环境
	系统	linux	linux_kernel	*	From (including) 4.14.0	Up to (excluding) 4.14.261
	运行在以下环境
	系统	linux	linux_kernel	*	From (including) 4.15.0	Up to (excluding) 4.19.224
	运行在以下环境
	系统	linux	linux_kernel	*	From (including) 4.20.0	Up to (excluding) 5.4.170
	运行在以下环境
	系统	linux	linux_kernel	*	From (including) 5.11.0	Up to (excluding) 5.15.13
	运行在以下环境
	系统	linux	linux_kernel	*	From (including) 5.5.0	Up to (excluding) 5.10.90

攻击路径

本地
攻击复杂度

困难
权限要求

管控权限
影响范围

有限影响
EXP成熟度

未验证
补丁情况

官方补丁
数据保密性

无影响
数据完整性

无影响
服务器危害

无影响
全网数量

N/A

CWE-ID	漏洞类型
CWE-416	释放后使用

中危 sctp：使用 call_rcu 释放端点 (CVE-2021-46929)

漏洞描述

解决建议

参考链接

受影响软件情况