CVE-2022-50243

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

sctp: handle the error returned from sctp_auth_asoc_init_active_key

When it returns an error from sctp_auth_asoc_init_active_key(), the active_key is actually not updated. The old sh_key will be freeed while its still used as active key in asoc. Then an use-after-free will be triggered when sending patckets, as found by syzbot:

sctp_auth_shkey_hold+0x22/0xa0 net/sctp/auth.c:112 sctp_set_owner_w net/sctp/socket.c:132 [inline] sctp_sendmsg_to_asoc+0xbd5/0x1a20 net/sctp/socket.c:1863 sctp_sendmsg+0x1053/0x1d50 net/sctp/socket.c:2025 inet_sendmsg+0x99/0xe0 net/ipv4/af_inet.c:819 sock_sendmsg_nosec net/socket.c:714 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:734

This patch is to fix it by not replacing the sh_key when it returns errors from sctp_auth_asoc_init_active_key() in sctp_auth_set_key(). For sctp_auth_set_active_key(), old active_key_id will be set back to asoc->active_key_id when the same thing happens.

Weakness

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/022152aaebe116a25c39818a07e175a8cd3c1e11
• https://git.kernel.org/stable/c/0f90099d18e3abdc01babf686f41f63fe04939c1
• https://git.kernel.org/stable/c/19d636b663e0e92951bba5fced929ca7fd25c552
• https://git.kernel.org/stable/c/382ff44716603a54f5fd238ddec6a2468e217612
• https://git.kernel.org/stable/c/3b0fcf5e29c0940e1169ce9c44f73edd98bdf12d
• https://git.kernel.org/stable/c/b8fa99a3a11bdd77fef6b4a97f1021eb30b5ba40
• https://git.kernel.org/stable/c/f65955340e0044f5c41ac799a01698ac7dee8a4e