diff options
| author | Jeff Layton <jlayton@kernel.org> | 2026-06-11 16:00:59 -0400 |
|---|---|---|
| committer | Chuck Lever <cel@kernel.org> | 2026-08-10 09:54:35 -0400 |
| commit | 641e5e20852359b8c31149be4598884e30652f60 (patch) | |
| tree | e851bc0733fa281b943ca36d8f81476eceaeeb9a /include/linux | |
| parent | 2327ba1d9546727a35b17888777e991f68a9b305 (diff) | |
lockd, nfsd: RCU-protect nlmsvc_ops dispatch
nlmsvc_ops is published by nfsd_lockd_init() and cleared by
nfsd_lockd_shutdown() with plain stores, while lockd dereferences
it unguarded from dispatch sites in fs/lockd/svcsubs.c. The pointer
targets nfsd's .rodata and the fopen/fclose callbacks live in nfsd's
.text, so a stale load after rmmod nfsd results in either a NULL
deref or a module-text use-after-free.
Declare nlmsvc_ops as __rcu, publish via rcu_assign_pointer(), clear
via RCU_INIT_POINTER() + synchronize_rcu(). Add a struct module
*owner field to nlmsvc_binding and pin the module across indirect
calls with try_module_get/module_put. When the binding is torn down,
fall back to fput() to avoid leaking struct file references.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Assisted-by: Claude:claude-opus-4-8
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://patch.msgid.link/20260611-nfsd-testing-v2-16-5b90e276f2d9@kernel.org
Signed-off-by: Chuck Lever <cel@kernel.org>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/lockd/bind.h | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/include/linux/lockd/bind.h b/include/linux/lockd/bind.h index b614e0deea72..db8207d4059f 100644 --- a/include/linux/lockd/bind.h +++ b/include/linux/lockd/bind.h @@ -16,17 +16,23 @@ struct svc_rqst; struct rpc_task; struct rpc_clnt; struct super_block; +struct module; -/* - * This is the set of functions for lockd->nfsd communication +/** + * struct nlmsvc_binding - lockd -> nfsd callback table + * @owner: module that provides this binding. + * @fopen: open a file by NFS file handle on behalf of an NLM request. + * @fclose: close a file that was previously opened via @fopen. + * Implementations MUST be semantically equivalent to fput(). */ struct nlmsvc_binding { + struct module *owner; int (*fopen)(struct svc_rqst *rqstp, struct nfs_fh *f, struct file **filp, int flags); void (*fclose)(struct file *filp); }; -extern const struct nlmsvc_binding *nlmsvc_ops; +extern const struct nlmsvc_binding __rcu *nlmsvc_ops; /* * Similar to nfs_client_initdata, but without the NFS-specific |