• Eric Dumazet's avatar
    net/rose: fix unbound loop in rose_loopback_timer() · 51ba221a
    Eric Dumazet authored
    [ Upstream commit 0453c682459583910d611a96de928f4442205493 ]
    
    This patch adds a limit on the number of skbs that fuzzers can queue
    into loopback_queue. 1000 packets for rose loopback seems more than enough.
    
    Then, since we now have multiple cpus in most linux hosts,
    we also need to limit the number of skbs rose_loopback_timer()
    can dequeue at each round.
    
    rose_loopback_queue() can be drop-monitor friendly, calling
    consume_skb() or kfree_skb() appropriately.
    
    Finally, use mod_timer() instead of del_timer() + add_timer()
    
    syzbot report was :
    
    rcu: INFO: rcu_preempt self-detected stall on CPU
    rcu:    0-...!: (10499 ticks this GP) idle=536/1/0x4000000000000002 softirq=103291/103291 fqs=34
    rcu:     (t=10500 jiffies g=140321 q=323)
    rcu: rcu_preempt kthread starved for 10426 jiffies! g140321 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=1
    rcu: RCU grace-period kthread stack dump:
    rcu_preempt     I29168    10      2 0x80000000
    Call Trace:
     context_switch kernel/sched/core.c:2877 [inline]
     __schedule+0x813/0x1cc0 kernel/sched/core.c:3518
     schedule+0x92/0x180 kernel/sched/core.c:3562
     schedule_timeout+0x4db/0xfd0 kernel/time/timer.c:1803
     rcu_gp_fqs_loop kernel/rcu/tree.c:1971 [inline]
     rcu_gp_kthread+0x962/0x17b0 kernel/rcu/tree.c:2128
     kthread+0x357/0x430 kernel/kthread.c:253
     ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352
    NMI backtrace for cpu 0
    CPU: 0 PID: 7632 Comm: kworker/0:4 Not tainted 5.1.0-rc5+ #172
    Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
    Workqueue: events iterate_cleanup_work
    Call Trace:
     <IRQ>
     __dump_stack lib/dump_stack.c:77 [inline]
     dump_stack+0x172/0x1f0 lib/dump_stack.c:113
     nmi_cpu_backtrace.cold+0x63/0xa4 lib/nmi_backtrace.c:101
     nmi_trigger_cpumask_backtrace+0x1be/0x236 lib/nmi_backtrace.c:62
     arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
     trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline]
     rcu_dump_cpu_stacks+0x183/0x1cf kernel/rcu/tree.c:1223
     print_cpu_stall kernel/rcu/tree.c:1360 [inline]
     check_cpu_stall kernel/rcu/tree.c:1434 [inline]
     rcu_pending kernel/rcu/tree.c:3103 [inline]
     rcu_sched_clock_irq.cold+0x500/0xa4a kernel/rcu/tree.c:2544
     update_process_times+0x32/0x80 kernel/time/timer.c:1635
     tick_sched_handle+0xa2/0x190 kernel/time/tick-sched.c:161
     tick_sched_timer+0x47/0x130 kernel/time/tick-sched.c:1271
     __run_hrtimer kernel/time/hrtimer.c:1389 [inline]
     __hrtimer_run_queues+0x33e/0xde0 kernel/time/hrtimer.c:1451
     hrtimer_interrupt+0x314/0x770 kernel/time/hrtimer.c:1509
     local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1035 [inline]
     smp_apic_timer_interrupt+0x120/0x570 arch/x86/kernel/apic/apic.c:1060
     apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:807
    RIP: 0010:__sanitizer_cov_trace_pc+0x0/0x50 kernel/kcov.c:95
    Code: 89 25 b4 6e ec 08 41 bc f4 ff ff ff e8 cd 5d ea ff 48 c7 05 9e 6e ec 08 00 00 00 00 e9 a4 e9 ff ff 90 90 90 90 90 90 90 90 90 <55> 48 89 e5 48 8b 75 08 65 48 8b 04 25 00 ee 01 00 65 8b 15 c8 60
    RSP: 0018:ffff8880ae807ce0 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13
    RAX: ffff88806fd40640 RBX: dffffc0000000000 RCX: ffffffff863fbc56
    RDX: 0000000000000100 RSI: ffffffff863fbc1d RDI: ffff88808cf94228
    RBP: ffff8880ae807d10 R08: ffff88806fd40640 R09: ffffed1015d00f8b
    R10: ffffed1015d00f8a R11: 0000000000000003 R12: ffff88808cf941c0
    R13: 00000000fffff034 R14: ffff8882166cd840 R15: 0000000000000000
     rose_loopback_timer+0x30d/0x3f0 net/rose/rose_loopback.c:91
     call_timer_fn+0x190/0x720 kernel/time/timer.c:1325
     expire_timers kernel/time/timer.c:1362 [inline]
     __run_timers kernel/time/timer.c:1681 [inline]
     __run_timers kernel/time/timer.c:1649 [inline]
     run_timer_softirq+0x652/0x1700 kernel/time/timer.c:1694
     __do_softirq+0x266/0x95a kernel/softirq.c:293
     do_softirq_own_stack+0x2a/0x40 arch/x86/entry/entry_64.S:1027
    
    Fixes: 1da177e4 ("Linux-2.6.12-rc2")
    Signed-off-by: 's avatarEric Dumazet <edumazet@google.com>
    Reported-by: 's avatarsyzbot <syzkaller@googlegroups.com>
    Signed-off-by: 's avatarDavid S. Miller <davem@davemloft.net>
    Signed-off-by: 's avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    51ba221a
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