CVE-2026-99251
Drivers: hv: Avoid infinite retry loop in init_vp_index()
What happened?
In the Linux kernel, the following vulnerability has been resolved:
Drivers: hv: Avoid infinite retry loop in init_vp_index()
There is a retry loop in init_vp_index() where the CPUs from a certain node are stripped out if they have already been in the allocated cpumask or not in HK_TYPE_MANAGED_IRQ housekeeping cpumask. If there is no CPU left, the allocated cpumask is ignored and the process is retried again. However, if the HK_TYPE_MANAGED_IRQ housekeeping cpumask turns out not to contain any CPU in that particular node, that will become an infinite retry loop. This particular problem was reported by sashiko [1]. This should rarely happen, but we still need to guard against this.
Fix this infinite loop problem by also skipping NUMA node that has no housekeeping CPU in the inner while loop of init_vp_index(). Also update the early abort check to check for the absence of online housekeeping CPUs instead of just the emptiness of the cpumask. As the outer for loop will only be reached if the housekeeping cpumask has at least one online CPU, a NUMA node with housekeeping CPUs will eventually be found.
Affected software and versions
| Software | Version information | Fixed version |
|---|---|---|
| LinuxLinux | affected: 6640b5df1a38801be6d0595c8cd2177d968d7ee0 to < b3993f6dc106ff416c7a613c631e1e0af451aed7; affected: 6640b5df1a38801be6d0595c8cd2177d968d7ee0 to < f561392afb44a8a42c54c1cfd3f33dace0b50537; affected: 6640b5df1a38801be6d0595c8cd2177d968d7ee0 to < 15dd3429f0e76ca071657e480cb7e6ff3a1af730; affected: 6640b5df1a38801be6d0595c8cd2177d968d7ee0 to < 7141331f2d245efc07175802a6bf76badec871ed; affected: 6640b5df1a38801be6d0595c8cd2177d968d7ee0 to < 95fec47cdbf747b81ab22affd7252dda6050ad0c; affected: 6640b5df1a38801be6d0595c8cd2177d968d7ee0 to < 32ea0a33e3a0fb7c10c601b43e1b2f6c06a3f5fd | See vendor advisory |
| LinuxLinux | affected: 5.19; unaffected: 0 to < 5.19; unaffected: 6.1.191 to ≤ 6.1.*; unaffected: 6.6.161 to ≤ 6.6.*; unaffected: 6.12.115 to ≤ 6.12.*; unaffected: 6.18.59 to ≤ 6.18.*; unaffected: 7.2.13 to ≤ 7.2.*; unaffected: 7.3 to ≤ * | See vendor advisory |
Version information comes from the source record and can include unaffected products and exceptions. Distribution packages may contain backported fixes: an older upstream version alone does not prove a server is affected.
Is it being exploited?
This CVE was not listed in the CISA catalogue at our last retrieval. This does not establish that exploitation is absent.
How to respond
- Confirm the product, installed package version, and any configuration requirements in the vendor advisory.
- Follow the vendor’s remediation or workaround guidance in the references below. Structured fixed-version data is unavailable here; the publisher’s description may include a fix or workaround.
- Restart affected services if required, then verify the running version. Known exploitation may warrant investigation as well as patching.
Sources and remediation references
- https://www.cve.org/CVERecord?id=CVE-2026-99251
- https://git.kernel.org/stable/c/b3993f6dc106ff416c7a613c631e1e0af451aed7
- https://git.kernel.org/stable/c/f561392afb44a8a42c54c1cfd3f33dace0b50537
- https://git.kernel.org/stable/c/15dd3429f0e76ca071657e480cb7e6ff3a1af730
- https://git.kernel.org/stable/c/7141331f2d245efc07175802a6bf76badec871ed
- https://git.kernel.org/stable/c/95fec47cdbf747b81ab22affd7252dda6050ad0c
- https://git.kernel.org/stable/c/32ea0a33e3a0fb7c10c601b43e1b2f6c06a3f5fd