CVE-2024-35985: sched/eevdf: Prevent vlag from going out of bounds in reweight_eevdf()
In the Linux kernel, the following vulnerability has been resolved:
sched/eevdf: Prevent vlag from going out of bounds in reweighteevdf()
It was possible to have pickeevdf() return NULL, which then causes a NULL-deref. This turned out to be due to entityeligible() returning falsely negative because of a s64 multiplcation overflow.
Specifically, reweighteevdf() computes the vlag without considering the limit placed upon vlag as updateentitylag() does, and then the scaling multiplication (remember that weight is 20bit fixed point) can overflow. This then leads to the new vruntime being weird which then causes the above entityeligible() to go side-ways and claim nothing is eligible.
Thus limit the range of vlag accordingly.
All this was quite rare, but fatal when it does happen.
Affected Software
Remediation
Event History
Frequently Asked Questions
What is the severity of CVE-2024-35985?
CVE-2024-35985 has a medium severity rating due to the potential for a NULL dereference leading to denial of service.
How do I fix CVE-2024-35985?
To fix CVE-2024-35985, update the kernel to a patched version such as 5.10.223-1, 5.10.226-1, 6.1.123-1, 6.1.128-1, 6.12.12-1, or 6.12.15-1.
Which Linux kernel versions are affected by CVE-2024-35985?
CVE-2024-35985 affects Linux kernel versions from 6.6.4 up to 6.6.30, as well as versions prior to 6.9-rc1.
What is the nature of the vulnerability in CVE-2024-35985?
CVE-2024-35985 is a vulnerability that allows for a NULL dereference when pick_eevdf() returns NULL due to an out-of-bounds access.
Is there a workaround for CVE-2024-35985 while waiting for a patch?
There is no documented workaround for CVE-2024-35985, so it is recommended to apply the patch as soon as possible.