From: Alexander Sverdlin alexander.sverdlin@nokia.com
commit b10252c7ae9c9d7c90552f88b544a44ee773af64 upstream.
Commit bd5ae9288d64 ("nfsd: register pernet ops last, unregister first") has re-opened rpc_pipefs_event() race against nfsd_net_id registration (register_pernet_subsys()) which has been fixed by commit bb7ffbf29e76 ("nfsd: fix nsfd startup race triggering BUG_ON").
Restore the order of register_pernet_subsys() vs register_cld_notifier(). Add WARN_ON() to prevent a future regression.
Crash info: Unable to handle kernel NULL pointer dereference at virtual address 0000000000000012 CPU: 8 PID: 345 Comm: mount Not tainted 5.4.144-... #1 pc : rpc_pipefs_event+0x54/0x120 [nfsd] lr : rpc_pipefs_event+0x48/0x120 [nfsd] Call trace: rpc_pipefs_event+0x54/0x120 [nfsd] blocking_notifier_call_chain rpc_fill_super get_tree_keyed rpc_fs_get_tree vfs_get_tree do_mount ksys_mount __arm64_sys_mount el0_svc_handler el0_svc
Fixes: bd5ae9288d64 ("nfsd: register pernet ops last, unregister first") Cc: stable@vger.kernel.org Signed-off-by: Alexander Sverdlin alexander.sverdlin@nokia.com Signed-off-by: J. Bruce Fields bfields@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/nfsd/nfs4recover.c | 1 + fs/nfsd/nfsctl.c | 14 +++++++------- 2 files changed, 8 insertions(+), 7 deletions(-)
--- a/fs/nfsd/nfs4recover.c +++ b/fs/nfsd/nfs4recover.c @@ -2177,6 +2177,7 @@ static struct notifier_block nfsd4_cld_b int register_cld_notifier(void) { + WARN_ON(!nfsd_net_id); return rpc_pipefs_notifier_register(&nfsd4_cld_block); }
--- a/fs/nfsd/nfsctl.c +++ b/fs/nfsd/nfsctl.c @@ -1526,12 +1526,9 @@ static int __init init_nfsd(void) int retval; printk(KERN_INFO "Installing knfsd (copyright (C) 1996 okir@monad.swb.de).\n");
- retval = register_cld_notifier(); - if (retval) - return retval; retval = nfsd4_init_slabs(); if (retval) - goto out_unregister_notifier; + return retval; retval = nfsd4_init_pnfs(); if (retval) goto out_free_slabs; @@ -1549,9 +1546,14 @@ static int __init init_nfsd(void) goto out_free_exports; retval = register_pernet_subsys(&nfsd_net_ops); if (retval < 0) + goto out_free_filesystem; + retval = register_cld_notifier(); + if (retval) goto out_free_all; return 0; out_free_all: + unregister_pernet_subsys(&nfsd_net_ops); +out_free_filesystem: unregister_filesystem(&nfsd_fs_type); out_free_exports: remove_proc_entry("fs/nfs/exports", NULL); @@ -1565,13 +1567,12 @@ out_free_stat: nfsd4_exit_pnfs(); out_free_slabs: nfsd4_free_slabs(); -out_unregister_notifier: - unregister_cld_notifier(); return retval; }
static void __exit exit_nfsd(void) { + unregister_cld_notifier(); unregister_pernet_subsys(&nfsd_net_ops); nfsd_drc_slab_free(); remove_proc_entry("fs/nfs/exports", NULL); @@ -1582,7 +1583,6 @@ static void __exit exit_nfsd(void) nfsd4_exit_pnfs(); nfsd_fault_inject_cleanup(); unregister_filesystem(&nfsd_fs_type); - unregister_cld_notifier(); }
MODULE_AUTHOR("Olaf Kirch okir@monad.swb.de");