On 05/17/2018 12:54 PM, Eric Dumazet wrote:
> syzkaller found that following program crashes the host :
>
> {
> int fd = socket(AF_SMC, SOCK_STREAM, 0);
> int val = 1;
>
> listen(fd, 0);
> shutdown(fd, SHUT_RDWR);
> setsockopt(fd, 6, TCP_NODELAY, &val, 4);
> }
>
> Simply initialize conn.tx_work & conn.send_lock at socket creation,
> rather than deeper in the stack.
>
> ODEBUG: assert_init not available (active state 0) object type: timer_list hint: (null)
> WARNING: CPU: 1 PID: 13988 at lib/debugobjects.c:329 debug_print_object+0x16a/0x210 lib/debugobjects.c:326
> Kernel panic - not syncing: panic_on_warn set ...
>
> CPU: 1 PID: 13988 Comm: syz-executor0 Not tainted 4.17.0-rc4+ #46
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> Call Trace:
> __dump_stack lib/dump_stack.c:77 [inline]
> dump_stack+0x1b9/0x294 lib/dump_stack.c:113
> panic+0x22f/0x4de kernel/panic.c:184
> __warn.cold.8+0x163/0x1b3 kernel/panic.c:536
> report_bug+0x252/0x2d0 lib/bug.c:186
> fixup_bug arch/x86/kernel/traps.c:178 [inline]
> do_error_trap+0x1de/0x490 arch/x86/kernel/traps.c:296
> do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:315
> invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:992
> RIP: 0010:debug_print_object+0x16a/0x210 lib/debugobjects.c:326
> RSP: 0018:ffff880197a37880 EFLAGS: 00010086
> RAX: 0000000000000061 RBX: 0000000000000005 RCX: ffffc90001ed0000
> RDX: 0000000000004aaf RSI: ffffffff8160f6f1 RDI: 0000000000000001
> RBP: ffff880197a378c0 R08: ffff8801aa7a0080 R09: ffffed003b5e3eb2
> R10: ffffed003b5e3eb2 R11: ffff8801daf1f597 R12: 0000000000000001
> R13: ffffffff88d96980 R14: ffffffff87fa19a0 R15: ffffffff81666ec0
> debug_object_assert_init+0x309/0x500 lib/debugobjects.c:692
> debug_timer_assert_init kernel/time/timer.c:724 [inline]
> debug_assert_init kernel/time/timer.c:776 [inline]
> del_timer+0x74/0x140 kernel/time/timer.c:1198
> try_to_grab_pending+0x439/0x9a0 kernel/workqueue.c:1223
> mod_delayed_work_on+0x91/0x250 kernel/workqueue.c:1592
> mod_delayed_work include/linux/workqueue.h:541 [inline]
> smc_setsockopt+0x387/0x6d0 net/smc/af_smc.c:1367
> __sys_setsockopt+0x1bd/0x390 net/socket.c:1903
> __do_sys_setsockopt net/socket.c:1914 [inline]
> __se_sys_setsockopt net/socket.c:1911 [inline]
> __x64_sys_setsockopt+0xbe/0x150 net/socket.c:1911
> do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
> entry_SYSCALL_64_after_hwframe+0x49/0xbe
>
This problem should no longer show up with yesterday's net-next commit
569bc6436568 ("net/smc: no tx work trigger for fallback sockets").
> Fixes: 01d2f7e2cdd3 ("net/smc: sockopts TCP_NODELAY and TCP_CORK")
> Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
> Cc: Ursula Braun <ubraun@xxxxxxxxxxxxx>
> Cc: linux-s390@xxxxxxxxxxxxxxx
> Reported-by: syzbot <syzkaller@xxxxxxxxxxxxxxxx>
> ---
> net/smc/af_smc.c | 2 ++
> net/smc/smc_tx.c | 4 +---
> net/smc/smc_tx.h | 1 +
> 3 files changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
> index d15762b057c0d8d4167feca9a4c41f0408604c37..6ad4f6c771c3fa63d3ae714dbe65879910963a21 100644
> --- a/net/smc/af_smc.c
> +++ b/net/smc/af_smc.c
> @@ -193,8 +193,10 @@ static struct sock *smc_sock_alloc(struct net *net, struct socket *sock,
> sk->sk_protocol = protocol;
> smc = smc_sk(sk);
> INIT_WORK(&smc->tcp_listen_work, smc_tcp_listen_work);
> + INIT_DELAYED_WORK(&smc->conn.tx_work, smc_tx_work);
> INIT_LIST_HEAD(&smc->accept_q);
> spin_lock_init(&smc->accept_q_lock);
> + spin_lock_init(&smc->conn.send_lock);
> sk->sk_prot->hash(sk);
> sk_refcnt_debug_inc(sk);
>
> diff --git a/net/smc/smc_tx.c b/net/smc/smc_tx.c
> index 58dfe0bd9d6075b5d3db97c659999b364b97da73..08a7de98bb031b5d2256e3238236108749e7ae39 100644
> --- a/net/smc/smc_tx.c
> +++ b/net/smc/smc_tx.c
> @@ -450,7 +450,7 @@ int smc_tx_sndbuf_nonempty(struct smc_connection *conn)
> /* Wakeup sndbuf consumers from process context
> * since there is more data to transmit
> */
> -static void smc_tx_work(struct work_struct *work)
> +void smc_tx_work(struct work_struct *work)
> {
> struct smc_connection *conn = container_of(to_delayed_work(work),
> struct smc_connection,
> @@ -512,6 +512,4 @@ void smc_tx_consumer_update(struct smc_connection *conn)
> void smc_tx_init(struct smc_sock *smc)
> {
> smc->sk.sk_write_space = smc_tx_write_space;
> - INIT_DELAYED_WORK(&smc->conn.tx_work, smc_tx_work);
> - spin_lock_init(&smc->conn.send_lock);
> }
> diff --git a/net/smc/smc_tx.h b/net/smc/smc_tx.h
> index 78255964fa4dc1c69f96548e035e74a167999a62..8f64b12bf03c1b52c599b1239784a404efe65dae 100644
> --- a/net/smc/smc_tx.h
> +++ b/net/smc/smc_tx.h
> @@ -27,6 +27,7 @@ static inline int smc_tx_prepared_sends(struct smc_connection *conn)
> return smc_curs_diff(conn->sndbuf_size, &sent, &prep);
> }
>
> +void smc_tx_work(struct work_struct *work);
> void smc_tx_init(struct smc_sock *smc);
> int smc_tx_sendmsg(struct smc_sock *smc, struct msghdr *msg, size_t len);
> int smc_tx_sndbuf_nonempty(struct smc_connection *conn);
>
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