From 8e948c365d9c10b685d1deb946bd833d6a9b43e0 Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Mon, 17 Jun 2024 07:54:08 -0400 Subject: [PATCH 1/2] nfsd: fix oops when reading pool_stats before server is started Sourbh reported an oops that is triggerable by trying to read the pool_stats procfile before nfsd had been started. Move the check for a NULL serv in svc_pool_stats_start above the mutex acquisition, and fix the stop routine not to unlock the mutex if there is no serv yet. Fixes: 7b207ccd9833 ("svc: don't hold reference for poolstats, only mutex.") Reported-by: Sourabh Jain Signed-off-by: Jeff Layton Tested-by: Sourabh Jain Signed-off-by: Chuck Lever --- net/sunrpc/svc_xprt.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c index dd86d7f1e97e..49a3bea33f9d 100644 --- a/net/sunrpc/svc_xprt.c +++ b/net/sunrpc/svc_xprt.c @@ -1421,12 +1421,13 @@ static void *svc_pool_stats_start(struct seq_file *m, loff_t *pos) dprintk("svc_pool_stats_start, *pidx=%u\n", pidx); + if (!si->serv) + return NULL; + mutex_lock(si->mutex); if (!pidx) return SEQ_START_TOKEN; - if (!si->serv) - return NULL; return pidx > si->serv->sv_nrpools ? NULL : &si->serv->sv_pools[pidx - 1]; } @@ -1458,7 +1459,8 @@ static void svc_pool_stats_stop(struct seq_file *m, void *p) { struct svc_info *si = m->private; - mutex_unlock(si->mutex); + if (si->serv) + mutex_unlock(si->mutex); } static int svc_pool_stats_show(struct seq_file *m, void *p) From da2c8fef130ec7197e2f91c7ed70a8c5bede4bea Mon Sep 17 00:00:00 2001 From: Lorenzo Bianconi Date: Mon, 17 Jun 2024 16:26:26 +0200 Subject: [PATCH 2/2] NFSD: grab nfsd_mutex in nfsd_nl_rpc_status_get_dumpit() Grab nfsd_mutex lock in nfsd_nl_rpc_status_get_dumpit routine and remove nfsd_nl_rpc_status_get_start() and nfsd_nl_rpc_status_get_done(). This patch fix the syzbot log reported below: INFO: task syz-executor.1:17770 blocked for more than 143 seconds. Not tainted 6.10.0-rc3-syzkaller-00022-gcea2a26553ac #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz-executor.1 state:D stack:23800 pid:17770 tgid:17767 ppid:11381 flags:0x00000006 Call Trace: context_switch kernel/sched/core.c:5408 [inline] __schedule+0x17e8/0x4a20 kernel/sched/core.c:6745 __schedule_loop kernel/sched/core.c:6822 [inline] schedule+0x14b/0x320 kernel/sched/core.c:6837 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6894 __mutex_lock_common kernel/locking/mutex.c:684 [inline] __mutex_lock+0x6a4/0xd70 kernel/locking/mutex.c:752 nfsd_nl_listener_get_doit+0x115/0x5d0 fs/nfsd/nfsctl.c:2124 genl_family_rcv_msg_doit net/netlink/genetlink.c:1115 [inline] genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline] genl_rcv_msg+0xb16/0xec0 net/netlink/genetlink.c:1210 netlink_rcv_skb+0x1e5/0x430 net/netlink/af_netlink.c:2564 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219 netlink_unicast_kernel net/netlink/af_netlink.c:1335 [inline] netlink_unicast+0x7ec/0x980 net/netlink/af_netlink.c:1361 netlink_sendmsg+0x8db/0xcb0 net/netlink/af_netlink.c:1905 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg+0x223/0x270 net/socket.c:745 ____sys_sendmsg+0x525/0x7d0 net/socket.c:2585 ___sys_sendmsg net/socket.c:2639 [inline] __sys_sendmsg+0x2b0/0x3a0 net/socket.c:2668 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f24ed27cea9 RSP: 002b:00007f24ee0080c8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007f24ed3b3f80 RCX: 00007f24ed27cea9 RDX: 0000000000000000 RSI: 0000000020000100 RDI: 0000000000000005 RBP: 00007f24ed2ebff4 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 Fixes: 1bd773b4f0c9 ("nfsd: hold nfsd_mutex across entire netlink operation") Fixes: bd9d6a3efa97 ("NFSD: add rpc_status netlink support") Signed-off-by: Lorenzo Bianconi Reviewed-by: Jeff Layton Signed-off-by: Chuck Lever --- Documentation/netlink/specs/nfsd.yaml | 2 -- fs/nfsd/netlink.c | 2 -- fs/nfsd/netlink.h | 3 -- fs/nfsd/nfsctl.c | 48 ++++++--------------------- 4 files changed, 11 insertions(+), 44 deletions(-) diff --git a/Documentation/netlink/specs/nfsd.yaml b/Documentation/netlink/specs/nfsd.yaml index d21234097167..6bda7a467301 100644 --- a/Documentation/netlink/specs/nfsd.yaml +++ b/Documentation/netlink/specs/nfsd.yaml @@ -123,8 +123,6 @@ operations: doc: dump pending nfsd rpc attribute-set: rpc-status dump: - pre: nfsd-nl-rpc-status-get-start - post: nfsd-nl-rpc-status-get-done reply: attributes: - xid diff --git a/fs/nfsd/netlink.c b/fs/nfsd/netlink.c index 62d2586d9902..529a75ecf22e 100644 --- a/fs/nfsd/netlink.c +++ b/fs/nfsd/netlink.c @@ -44,9 +44,7 @@ static const struct nla_policy nfsd_listener_set_nl_policy[NFSD_A_SERVER_SOCK_AD static const struct genl_split_ops nfsd_nl_ops[] = { { .cmd = NFSD_CMD_RPC_STATUS_GET, - .start = nfsd_nl_rpc_status_get_start, .dumpit = nfsd_nl_rpc_status_get_dumpit, - .done = nfsd_nl_rpc_status_get_done, .flags = GENL_CMD_CAP_DUMP, }, { diff --git a/fs/nfsd/netlink.h b/fs/nfsd/netlink.h index e3724637d64d..2e132ef328f8 100644 --- a/fs/nfsd/netlink.h +++ b/fs/nfsd/netlink.h @@ -15,9 +15,6 @@ extern const struct nla_policy nfsd_sock_nl_policy[NFSD_A_SOCK_TRANSPORT_NAME + 1]; extern const struct nla_policy nfsd_version_nl_policy[NFSD_A_VERSION_ENABLED + 1]; -int nfsd_nl_rpc_status_get_start(struct netlink_callback *cb); -int nfsd_nl_rpc_status_get_done(struct netlink_callback *cb); - int nfsd_nl_rpc_status_get_dumpit(struct sk_buff *skb, struct netlink_callback *cb); int nfsd_nl_threads_set_doit(struct sk_buff *skb, struct genl_info *info); diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c index 202140df8f82..533b65057e18 100644 --- a/fs/nfsd/nfsctl.c +++ b/fs/nfsd/nfsctl.c @@ -1460,28 +1460,6 @@ static int create_proc_exports_entry(void) unsigned int nfsd_net_id; -/** - * nfsd_nl_rpc_status_get_start - Prepare rpc_status_get dumpit - * @cb: netlink metadata and command arguments - * - * Return values: - * %0: The rpc_status_get command may proceed - * %-ENODEV: There is no NFSD running in this namespace - */ -int nfsd_nl_rpc_status_get_start(struct netlink_callback *cb) -{ - struct nfsd_net *nn = net_generic(sock_net(cb->skb->sk), nfsd_net_id); - int ret = -ENODEV; - - mutex_lock(&nfsd_mutex); - if (nn->nfsd_serv) - ret = 0; - else - mutex_unlock(&nfsd_mutex); - - return ret; -} - static int nfsd_genl_rpc_status_compose_msg(struct sk_buff *skb, struct netlink_callback *cb, struct nfsd_genl_rqstp *rqstp) @@ -1558,8 +1536,16 @@ static int nfsd_genl_rpc_status_compose_msg(struct sk_buff *skb, int nfsd_nl_rpc_status_get_dumpit(struct sk_buff *skb, struct netlink_callback *cb) { - struct nfsd_net *nn = net_generic(sock_net(skb->sk), nfsd_net_id); int i, ret, rqstp_index = 0; + struct nfsd_net *nn; + + mutex_lock(&nfsd_mutex); + + nn = net_generic(sock_net(skb->sk), nfsd_net_id); + if (!nn->nfsd_serv) { + ret = -ENODEV; + goto out_unlock; + } rcu_read_lock(); @@ -1636,22 +1622,10 @@ int nfsd_nl_rpc_status_get_dumpit(struct sk_buff *skb, ret = skb->len; out: rcu_read_unlock(); - - return ret; -} - -/** - * nfsd_nl_rpc_status_get_done - rpc_status_get dumpit post-processing - * @cb: netlink metadata and command arguments - * - * Return values: - * %0: Success - */ -int nfsd_nl_rpc_status_get_done(struct netlink_callback *cb) -{ +out_unlock: mutex_unlock(&nfsd_mutex); - return 0; + return ret; } /**