CVE-2021-47593

mptcp: clear 'kern' flag from fallback sockets

Description

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 [..]

Category

5.5
CVSS
Severity: Medium
CVSS 3.1 •
EPSS 0.04%
Affected: Linux Linux
Affected: Linux Linux
Published at:
Updated at:

References

Link Tags
https://git.kernel.org/stable/c/451f1eded7f56e93aaf52eb547ba97742d9c0e97 patch
https://git.kernel.org/stable/c/c26ac0ea3a91c210cf90452e625dc441adf3e549 patch
https://git.kernel.org/stable/c/d6692b3b97bdc165d150f4c1505751a323a80717 patch

Frequently Asked Questions

What is the severity of CVE-2021-47593?
CVE-2021-47593 has been scored as a medium severity vulnerability.
How to fix CVE-2021-47593?
To fix CVE-2021-47593, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2021-47593 being actively exploited in the wild?
As for now, there are no information to confirm that CVE-2021-47593 is being actively exploited. According to its EPSS score, there is a ~0% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2021-47593?
CVE-2021-47593 affects Linux Linux, Linux Linux.
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