CVE-2026-93212

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

nfsd: guard nfsd_serv deref in nfsd_file_net_dispose

nfsd_file_net_dispose() is the consumer side of l->freeme: the nfsd

service thread loop calls it to drain entries that the filecache

garbage collector and shrinker append via

nfsd_file_dispose_list_delayed(). During per-net teardown,

nn->nfsd_serv is cleared before the filecache laundrette is shut

down, so the service thread can still run a dispose pass that finds

more than eight entries on l->freeme and dereferences a NULL

svc_serv:

nfsd service thread loop

nfsd_file_net_dispose(nn)

if (!list_empty(&l->freeme)) {

...

svc_wake_up(nn->nfsd_serv); /* nn->nfsd_serv == NULL */

}

The sibling helper nfsd_file_dispose_list_delayed() already documents

this ordering and caches nn->nfsd_serv into a local before testing it

for NULL. nfsd_file_net_dispose() was introduced with the same raw

svc_wake_up(nn->nfsd_serv) call and never picked up the guard.

Fix by loading nn->nfsd_serv into a local svc_serv pointer and only

calling svc_wake_up() when it is non-NULL, matching the pattern in

nfsd_file_dispose_list_delayed().