CVE-2026-89685

Summary

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

nfsd: fix clock domain mismatch in clients_still_reclaiming()

clients_still_reclaiming() computes a deadline from nn->boot_time (CLOCK_REALTIME, ~1.7 billion) but compares it against ktime_get_boottime_seconds() (CLOCK_BOOTTIME, seconds since boot). The comparison is always false — it would take ~54 years of uptime for BOOTTIME to exceed the REALTIME-derived deadline.

This means any client can hold the server in grace indefinitely by sending CLAIM_PREVIOUS OPEN requests, blocking all non-reclaim operations for all other clients.

Add boot_time_bt (CLOCK_BOOTTIME) alongside the existing boot_time and use it for the deadline computation. boot_time (CLOCK_REALTIME) is preserved for its cl_boot clientid-nonce role.

Affected Software

VendorProductVersion RangeStatus
LinuxLinux20b7d86f29d39e8ae19bb29c24ffee70dc385ddf < f9cec313efb2fd18d962aad738a4892bce806016affected
LinuxLinux20b7d86f29d39e8ae19bb29c24ffee70dc385ddf < 9843649196221152b6e5d138a3ce859bdaae1d96affected
LinuxLinux20b7d86f29d39e8ae19bb29c24ffee70dc385ddf < 09ea3eb9a518565f5bca386e81b993ed8825f5e8affected
LinuxLinux5.6affected
LinuxLinux0 < 5.6unaffected
LinuxLinux6.18.51 <= 6.18.*unaffected
LinuxLinux7.2.4 <= 7.2.*unaffected
LinuxLinux7.3-rc1 <= *unaffected

Weaknesses

References