CVE-2025-21646

Summary

In the Linux kernel, the following vulnerability has been resolved:

afs: Fix the maximum cell name length

The kafs filesystem limits the maximum length of a cell to 256 bytes, but a problem occurs if someone actually does that: kafs tries to create a directory under /proc/net/afs/ with the name of the cell, but that fails with a warning:

    WARNING: CPU: 0 PID: 9 at fs/proc/generic.c:405

because procfs limits the maximum filename length to 255.

However, the DNS limits the maximum lookup length and, by extension, the maximum cell name, to 255 less two (length count and trailing NUL).

Fix this by limiting the maximum acceptable cellname length to 253. This also allows us to be sure we can create the "/afs/.<cell>/" mountpoint too.

Further, split the YFS VL record cell name maximum to be the 256 allowed by the protocol and ignore the record retrieved by YFSVL.GetCellName if it exceeds 253.

Affected Software

VendorProductVersion RangeStatus
LinuxLinuxc3e9f888263bb4df11cbd623ceced02081cb2f9f < 9340385468d056bb700b8f28df236b81fc86a079affected
LinuxLinuxc3e9f888263bb4df11cbd623ceced02081cb2f9f < 7cb3e77e9b4e6ffa325a5559393d3283c9af3d01affected
LinuxLinuxc3e9f888263bb4df11cbd623ceced02081cb2f9f < aabe47cf5ac5e1db2ae0635f189d836f67024904affected
LinuxLinuxc3e9f888263bb4df11cbd623ceced02081cb2f9f < 7673030efe0f8ca1056d3849d61784c6caa052afaffected
LinuxLinuxc3e9f888263bb4df11cbd623ceced02081cb2f9f < 7922b1f058fe24a93730511dd0ae2e1630920096affected
LinuxLinuxc3e9f888263bb4df11cbd623ceced02081cb2f9f < 8fd56ad6e7c90ac2bddb0741c6b248c8c5d56ac8affected
LinuxLinux5.8affected
LinuxLinux0 < 5.8unaffected
LinuxLinux5.10.234 <= 5.10.*unaffected
LinuxLinux5.15.177 <= 5.15.*unaffected
LinuxLinux6.1.125 <= 6.1.*unaffected
LinuxLinux6.6.72 <= 6.6.*unaffected
LinuxLinux6.12.10 <= 6.12.*unaffected
LinuxLinux6.13 <= *unaffected

Weaknesses

ADP Enrichment

CVE Program Container

Additional References

References