In the Linux kernel, the following vulnerability has been resolved:
mptcp: clear ‘kern’ flag from fallback sockets
The mptcp ULP extension relies on sk->sk_sock_kern being set correctly:
It prevents setsockopt(fd, IPPROTO_TCP, TCP_ULP, “mptcp”, 6); from
working for plain tcp sockets (any userspace-exposed socket).
But in case of fallback, accept() can return a plain tcp sk.
In such case, sk is still tagged as ‘kernel’ and setsockopt will work.
This will crash the kernel, The subflow extension has a NULL ctx->conn
mptcp socket:
BUG: KASAN: null-ptr-deref in subflow_data_ready+0x181/0x2b0
Call Trace:
tcp_data_ready+0xf8/0x370
[…]
OS | Version | Architecture | Package | Version | Filename |
---|---|---|---|---|---|
ubuntu | 18.04 | noarch | linux | < any | UNKNOWN |
ubuntu | 20.04 | noarch | linux | < any | UNKNOWN |
ubuntu | 22.04 | noarch | linux | < any | UNKNOWN |
ubuntu | 23.10 | noarch | linux | < any | UNKNOWN |
ubuntu | 24.04 | noarch | linux | < any | UNKNOWN |
ubuntu | 14.04 | noarch | linux | < any | UNKNOWN |
ubuntu | 16.04 | noarch | linux | < any | UNKNOWN |
ubuntu | 18.04 | noarch | linux-aws | < any | UNKNOWN |
ubuntu | 20.04 | noarch | linux-aws | < any | UNKNOWN |
ubuntu | 22.04 | noarch | linux-aws | < any | UNKNOWN |
git.kernel.org/linus/d6692b3b97bdc165d150f4c1505751a323a80717 (5.16-rc6)
git.kernel.org/stable/c/451f1eded7f56e93aaf52eb547ba97742d9c0e97
git.kernel.org/stable/c/c26ac0ea3a91c210cf90452e625dc441adf3e549
git.kernel.org/stable/c/d6692b3b97bdc165d150f4c1505751a323a80717
launchpad.net/bugs/cve/CVE-2021-47593
nvd.nist.gov/vuln/detail/CVE-2021-47593
security-tracker.debian.org/tracker/CVE-2021-47593
www.cve.org/CVERecord?id=CVE-2021-47593