CVE-2024-50186: net: explicitly clear the sk pointer, when pf->create fails
In the Linux kernel, the following vulnerability has been resolved:
net: explicitly clear the sk pointer, when pf->create fails
We have recently noticed the exact same KASAN splat as in commit 6cd4a78d962b ("net: do not leave a dangling sk pointer, when socket creation fails"). The problem is that commit did not fully address the problem, as some pf->create implementations do not use skcommonrelease in their error paths.
For example, we can use the same reproducer as in the above commit, but changing ping to arping. arping uses AFPACKET socket and if packetcreate fails, it will just skfree the allocated sk object.
While we could chase all the pf->create implementations and make sure they NULL the freed sk object on error from the socket, we can't guarantee future protocols will not make the same mistake.
So it is easier to just explicitly NULL the sk pointer upon return from pf->create in sockcreate. We do know that pf->create always releases the allocated sk object on error, so if the pointer is not NULL, it is definitely dangling.
Other sources
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— Launchpad
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
debian/linuxto a version that resolves this vulnerability.Fixed in 5.10.223-1Fixed in 5.10.234-1Fixed in 6.1.129-1Fixed in 6.1.135-1Fixed in 6.12.25-1Fixed in 6.12.27-1 - Upgrade
Upgrade
debian/linux-6.1to a version that resolves this vulnerability.Fixed in 6.1.129-1~deb11u1 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 5.15.173.1-1 - Configuration
In __sock_create, explicitly set/clear the freed sk pointer to NULL when pf->create fails, because some pf->create implementations do not use sk_common_release in their error paths and may leave a dangling sk pointer.
Linux kernel networking (sock creation path: __sock_create) Explicitly clear NULL dangling sk pointer when pf->create fails = NULL sk pointer on pf->create error return from __sock_create
Event History
Frequently Asked Questions
What is the severity of CVE-2024-50186?
CVE-2024-50186 has a medium severity rating due to its impact on potential security risks in the Linux kernel.
How do I fix CVE-2024-50186?
To fix CVE-2024-50186, you should upgrade to the patched versions such as linux 5.10.223-1, 5.10.226-1, or any subsequent versions mentioned in the vulnerability details.
Which versions of the Linux kernel are affected by CVE-2024-50186?
CVE-2024-50186 affects multiple versions of the Linux kernel, particularly those before the specified remedial versions such as 5.10.223-1 and later.
What is the cause of CVE-2024-50186?
CVE-2024-50186 is caused by a failure to explicitly clear the sk pointer in the Linux kernel during socket creation, leading to potential security vulnerabilities.
Can CVE-2024-50186 be exploited remotely?
Yes, CVE-2024-50186 can potentially be exploited remotely, emphasizing the importance of applying recommended patches promptly.