CVE-2026-90149

Summary

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

NFSv4/flexfiles: fix NULL dereference for NFSv4.0 data servers

flexfiles accepts NFSv4.0 data servers, but two NFSv4 code paths assume the data server client has a session. Unlike NFSv4.1+, an NFSv4.0 client has no session (clp->cl_session is NULL; it uses clp->cl_slot_tbl), so I/O to a v4.0 flexfiles DS oopses:

  • nfs4_init_ds_session() dereferences clp->cl_session->session_state while seeding the DS lease. It also only seeds cl_lease_time when NFS4_SESSION_INITING is set; without a session that never happens, so cl_lease_time stays 0 and nfs4_renew_state() busy-loops, requeuing every 5 seconds. Seed the lease whenever there is no session and return before touching session state.

  • ff_layout_async_handle_error_v4() dereferences clp->cl_session->fc_slot_table on every DS I/O error. Fall back to the v4.0 transport slot table (clp->cl_slot_tbl) when there is no session.

Affected Software

VendorProductVersion RangeStatus
LinuxLinuxa7878ca140084ec267ede48fce64d7e60f6d873e < 163c16e01f53fc8eb8d0f3484ae6c382265ecbbdaffected
LinuxLinuxa7878ca140084ec267ede48fce64d7e60f6d873e < 436a214514e24103159aea455147d58b44a8a585affected
LinuxLinuxa7878ca140084ec267ede48fce64d7e60f6d873e < 2b03ebbf8d5e8f6af4ecd6c65375232dd1ec32ccaffected
LinuxLinux4.12affected
LinuxLinux0 < 4.12unaffected
LinuxLinux6.18.52 <= 6.18.*unaffected
LinuxLinux7.2.6 <= 7.2.*unaffected
LinuxLinux7.3-rc1 <= *unaffected

Weaknesses

References