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    Subject[PATCH 4.15 113/146] netfilter: IDLETIMER: be syzkaller friendly
    Date
    4.15-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Eric Dumazet <edumazet@google.com>

    commit cfc2c740533368b96e2be5e0a4e8c3cace7d9814 upstream.

    We had one report from syzkaller [1]

    First issue is that INIT_WORK() should be done before mod_timer()
    or we risk timer being fired too soon, even with a 1 second timer.

    Second issue is that we need to reject too big info->timeout
    to avoid overflows in msecs_to_jiffies(info->timeout * 1000), or
    risk looping, if result after overflow is 0.

    [1]
    WARNING: CPU: 1 PID: 5129 at kernel/workqueue.c:1444 __queue_work+0xdf4/0x1230 kernel/workqueue.c:1444
    Kernel panic - not syncing: panic_on_warn set ...

    CPU: 1 PID: 5129 Comm: syzkaller159866 Not tainted 4.16.0-rc1+ #230
    Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
    Call Trace:
    <IRQ>
    __dump_stack lib/dump_stack.c:17 [inline]
    dump_stack+0x194/0x257 lib/dump_stack.c:53
    panic+0x1e4/0x41c kernel/panic.c:183
    __warn+0x1dc/0x200 kernel/panic.c:547
    report_bug+0x211/0x2d0 lib/bug.c:184
    fixup_bug.part.11+0x37/0x80 arch/x86/kernel/traps.c:178
    fixup_bug arch/x86/kernel/traps.c:247 [inline]
    do_error_trap+0x2d7/0x3e0 arch/x86/kernel/traps.c:296
    do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:315
    invalid_op+0x22/0x40 arch/x86/entry/entry_64.S:988
    RIP: 0010:__queue_work+0xdf4/0x1230 kernel/workqueue.c:1444
    RSP: 0018:ffff8801db507538 EFLAGS: 00010006
    RAX: ffff8801aeb46080 RBX: ffff8801db530200 RCX: ffffffff81481404
    RDX: 0000000000000100 RSI: ffffffff86b42640 RDI: 0000000000000082
    RBP: ffff8801db507758 R08: 1ffff1003b6a0de5 R09: 000000000000000c
    R10: ffff8801db5073f0 R11: 0000000000000020 R12: 1ffff1003b6a0eb6
    R13: ffff8801b1067ae0 R14: 00000000000001f8 R15: dffffc0000000000
    queue_work_on+0x16a/0x1c0 kernel/workqueue.c:1488
    queue_work include/linux/workqueue.h:488 [inline]
    schedule_work include/linux/workqueue.h:546 [inline]
    idletimer_tg_expired+0x44/0x60 net/netfilter/xt_IDLETIMER.c:116
    call_timer_fn+0x228/0x820 kernel/time/timer.c:1326
    expire_timers kernel/time/timer.c:1363 [inline]
    __run_timers+0x7ee/0xb70 kernel/time/timer.c:1666
    run_timer_softirq+0x4c/0x70 kernel/time/timer.c:1692
    __do_softirq+0x2d7/0xb85 kernel/softirq.c:285
    invoke_softirq kernel/softirq.c:365 [inline]
    irq_exit+0x1cc/0x200 kernel/softirq.c:405
    exiting_irq arch/x86/include/asm/apic.h:541 [inline]
    smp_apic_timer_interrupt+0x16b/0x700 arch/x86/kernel/apic/apic.c:1052
    apic_timer_interrupt+0xa9/0xb0 arch/x86/entry/entry_64.S:829
    </IRQ>
    RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:777 [inline]
    RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:160 [inline]
    RIP: 0010:_raw_spin_unlock_irqrestore+0x5e/0xba kernel/locking/spinlock.c:184
    RSP: 0018:ffff8801c20173c8 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff12
    RAX: dffffc0000000000 RBX: 0000000000000282 RCX: 0000000000000006
    RDX: 1ffffffff0d592cd RSI: 1ffff10035d68d23 RDI: 0000000000000282
    RBP: ffff8801c20173d8 R08: 1ffff10038402e47 R09: 0000000000000000
    R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff8820e5c8
    R13: ffff8801b1067ad8 R14: ffff8801aea7c268 R15: ffff8801aea7c278
    __debug_object_init+0x235/0x1040 lib/debugobjects.c:378
    debug_object_init+0x17/0x20 lib/debugobjects.c:391
    __init_work+0x2b/0x60 kernel/workqueue.c:506
    idletimer_tg_create net/netfilter/xt_IDLETIMER.c:152 [inline]
    idletimer_tg_checkentry+0x691/0xb00 net/netfilter/xt_IDLETIMER.c:213
    xt_check_target+0x22c/0x7d0 net/netfilter/x_tables.c:850
    check_target net/ipv6/netfilter/ip6_tables.c:533 [inline]
    find_check_entry.isra.7+0x935/0xcf0 net/ipv6/netfilter/ip6_tables.c:575
    translate_table+0xf52/0x1690 net/ipv6/netfilter/ip6_tables.c:744
    do_replace net/ipv6/netfilter/ip6_tables.c:1160 [inline]
    do_ip6t_set_ctl+0x370/0x5f0 net/ipv6/netfilter/ip6_tables.c:1686
    nf_sockopt net/netfilter/nf_sockopt.c:106 [inline]
    nf_setsockopt+0x67/0xc0 net/netfilter/nf_sockopt.c:115
    ipv6_setsockopt+0x10b/0x130 net/ipv6/ipv6_sockglue.c:927
    udpv6_setsockopt+0x45/0x80 net/ipv6/udp.c:1422
    sock_common_setsockopt+0x95/0xd0 net/core/sock.c:2976
    SYSC_setsockopt net/socket.c:1850 [inline]
    SyS_setsockopt+0x189/0x360 net/socket.c:1829
    do_syscall_64+0x282/0x940 arch/x86/entry/common.c:287

    Fixes: 0902b469bd25 ("netfilter: xtables: idletimer target implementation")
    Signed-off-by: Eric Dumazet <edumazet@google.com>
    Reported-by: syzkaller <syzkaller@googlegroups.com>
    Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    net/netfilter/xt_IDLETIMER.c | 9 ++++++---
    1 file changed, 6 insertions(+), 3 deletions(-)

    --- a/net/netfilter/xt_IDLETIMER.c
    +++ b/net/netfilter/xt_IDLETIMER.c
    @@ -146,11 +146,11 @@ static int idletimer_tg_create(struct id
    timer_setup(&info->timer->timer, idletimer_tg_expired, 0);
    info->timer->refcnt = 1;

    + INIT_WORK(&info->timer->work, idletimer_tg_work);
    +
    mod_timer(&info->timer->timer,
    msecs_to_jiffies(info->timeout * 1000) + jiffies);

    - INIT_WORK(&info->timer->work, idletimer_tg_work);
    -
    return 0;

    out_free_attr:
    @@ -191,7 +191,10 @@ static int idletimer_tg_checkentry(const
    pr_debug("timeout value is zero\n");
    return -EINVAL;
    }
    -
    + if (info->timeout >= INT_MAX / 1000) {
    + pr_debug("timeout value is too big\n");
    + return -EINVAL;
    + }
    if (info->label[0] == '\0' ||
    strnlen(info->label,
    MAX_IDLETIMER_LABEL_SIZE) == MAX_IDLETIMER_LABEL_SIZE) {

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