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Date: Mon, 17 Jun 2024 09:26:30 -0700
From: syzbot <syzbot+4207adf14e7c0981d28d@...kaller.appspotmail.com>
To: lorenzo@...nel.org
Cc: chuck.lever@...cle.com, dai.ngo@...cle.com, jlayton@...nel.org,
kolga@...app.com, linux-kernel@...r.kernel.org, linux-nfs@...r.kernel.org,
lorenzo@...nel.org, neilb@...e.de, syzkaller-bugs@...glegroups.com,
tom@...pey.com
Subject: Re: [syzbot] [nfs?] INFO: task hung in nfsd_nl_listener_get_doit
>> Hello,
>>
>> syzbot found the following issue on:
>>
>> HEAD commit: cea2a26553ac mailmap: Add my outdated addresses to the map..
>> git tree: upstream
>> console output: https://syzkaller.appspot.com/x/log.txt?x=169fd8ee980000
>> kernel config: https://syzkaller.appspot.com/x/.config?x=fa0ce06dcc735711
>> dashboard link: https://syzkaller.appspot.com/bug?extid=4207adf14e7c0981d28d
>> compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
>>
>> Unfortunately, I don't have any reproducer for this issue yet.
>>
>> Downloadable assets:
>> disk image: https://storage.googleapis.com/syzbot-assets/1f7ce933512f/disk-cea2a265.raw.xz
>> vmlinux: https://storage.googleapis.com/syzbot-assets/0ce3b9940616/vmlinux-cea2a265.xz
>> kernel image: https://storage.googleapis.com/syzbot-assets/19e24094ea37/bzImage-cea2a265.xz
>>
>> IMPORTANT: if you fix the issue, please add the following tag to the commit:
>> Reported-by: syzbot+4207adf14e7c0981d28d@...kaller.appspotmail.com
>>
>> 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:
>> <TASK>
>> 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
>>
>>
>> ---
>> This report is generated by a bot. It may contain errors.
>> See https://goo.gl/tpsmEJ for more information about syzbot.
>> syzbot engineers can be reached at syzkaller@...glegroups.com.
>>
>> syzbot will keep track of this issue. See:
>> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
>>
>> If the report is already addressed, let syzbot know by replying with:
>> #syz fix: exact-commit-title
>>
>> If you want to overwrite report's subsystems, reply with:
>> #syz set subsystems: new-subsystem
>> (See the list of subsystem names on the web dashboard)
>>
>> If the report is a duplicate of another one, reply with:
>> #syz dup: exact-subject-of-another-report
>>
>> If you want to undo deduplication, reply with:
>> #syz undup
>>
>
> #syz test https://git.kernel.org/pub/scm/linux/kernel/git/cel/linux.git 4ddfda417a50
This crash does not have a reproducer. I cannot test it.
>
> From be9676fba16c0b8769c3b6094f35da39b1ba3953 Mon Sep 17 00:00:00 2001
> Message-ID: <be9676fba16c0b8769c3b6094f35da39b1ba3953.1718640518.git.lorenzo@...nel.org>
> From: Lorenzo Bianconi <lorenzo@...nel.org>
> Date: Mon, 17 Jun 2024 16:26:26 +0200
> Subject: [PATCH] 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:
> <TASK>
> 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 <lorenzo@...nel.org>
> ---
> 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 5a98e5a06c68..c87658114852 100644
> --- a/Documentation/netlink/specs/nfsd.yaml
> +++ b/Documentation/netlink/specs/nfsd.yaml
> @@ -132,8 +132,6 @@ 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 137701153c9e..ca54aa583530 100644
> --- a/fs/nfsd/netlink.c
> +++ b/fs/nfsd/netlink.c
> @@ -49,9 +49,7 @@ static const struct nla_policy nfsd_pool_mode_set_nl_policy[NFSD_A_POOL_MODE_MOD
> 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 9459547de04e..8eb903f24c41 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 e5d2cc74ef77..78091a73b33b 100644
> --- a/fs/nfsd/nfsctl.c
> +++ b/fs/nfsd/nfsctl.c
> @@ -1468,28 +1468,6 @@ 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)
> @@ -1566,8 +1544,16 @@ 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();
>
> @@ -1644,22 +1630,10 @@ 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;
> }
>
> /**
> --
> 2.45.1
>
>
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