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    Subject[CHECKER] potential races in kernel/*.c mm/*.c net/*ipv4*.c
    Date
    Hi All,

    here are a few more potential races from checking the directories:
    kernel/*.c
    mm/*.c
    net/*ipv4*.c
    arch/i386/kernel/*.c

    which seem relatively more important that other directories. [If there
    are other subdirs that a worth checking let me know --- I am trying to
    ensure that if we release race bugs someone will care enough to look
    at them.]

    The message format is a bit confusing. It gives the places where the
    checker thinks there are errors, and then a short list of examples
    that made it think that an omitted lock protects the variable.

    I do apologize if there are false positives --- I've gone over these,
    but sometimes it's very hard to tell if state needs to be protected.

    Dawson
    -------------------------------------------------------
    BUG? pair: lock=<struct sighand_struct.siglock>, var=<recalc_sigpending>
    z score=0.90
    singles = 1
    last = 8
    global-var
    1 error out of 11 uses:
    /u2/engler/mc/oses/linux/linux-2.5.62/kernel/ptrace.c:339:ptrace_notify: ERROR: var <recalc_sigpending> not protected by <struct sighand_struct.siglock>(pop=11, s=10) [locked=0] [seen_lock=1]


    looks like a bug:

    void ptrace_notify(int exit_code)
    {
    /* Let the debugger run. */
    current->exit_code = exit_code;
    set_current_state(TASK_STOPPED);
    notify_parent(current, SIGCHLD);
    schedule();

    // Signals sent while we were stopped might set TIF_SIGPENDING.
    recalc_sigpending();

    other places are carefully guard recalc_sigpending with
    siglock:
    spin_lock_irqsave(&current->sighand->siglock, flags);
    current->notifier = NULL;
    current->notifier_data = NULL;
    recalc_sigpending();
    spin_unlock_irqrestore(&current->sighand->siglock, flags);

    ====================================
    10 examples:
    /u2/engler/mc/oses/linux/linux-2.5.62/kernel/signal.c:403:unblock_all_signals: NOTE: var <recalc_sigpending> protected by <struct sighand_struct.siglock> [annot=single] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/kernel/signal.c:unblock_all_signals:400] (pop=11, s=10)
    /u2/engler/mc/oses/linux/linux-2.5.62/kernel/signal.c:2183:sys_ssetmask: NOTE: var <recalc_sigpending> protected by <struct sighand_struct.siglock> [annot=last] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/kernel/signal.c:sys_ssetmask:2178] (pop=11, s=10)
    /u2/engler/mc/oses/linux/linux-2.5.62/kernel/signal.c:2115:sys_sigprocmask: NOTE: var <recalc_sigpending> protected by <struct sighand_struct.siglock> [annot=last] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/kernel/signal.c:sys_sigprocmask:2096] (pop=11, s=10)
    /u2/engler/mc/oses/linux/linux-2.5.62/kernel/signal.c:1848:sys_rt_sigtimedwait: NOTE: var <recalc_sigpending> protected by <struct sighand_struct.siglock> [annot=last] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/kernel/signal.c:sys_rt_sigtimedwait:1844] (pop=11, s=10)
    /u2/engler/mc/oses/linux/linux-2.5.62/arch/i386/kernel/signal.c:43:sys_sigsuspend: NOTE: var <recalc_sigpending> protected by <struct sighand_struct.siglock> [annot=last] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/arch/i386/kernel/signal.c:sys_sigsuspend:40] (pop=11, s=10)
    /u2/engler/mc/oses/linux/linux-2.5.62/kernel/signal.c:1656:sigprocmask: NOTE: var <recalc_sigpending> protected by <struct sighand_struct.siglock> [annot=last] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/kernel/signal.c:sigprocmask:1640] (pop=11, s=10)
    -------------------------------------------------------
    BUG? pair: lock=<socket_lock_t.slock>, var=<struct sock.backlog.tail>
    z score=2.81
    first = 38
    1 error out of 41 uses:
    /u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/tcp.c:1580:tcp_recvmsg: ERROR: var <struct sock.backlog.tail> not protected by <socket_lock_t.slock>(pop=41, s=40) [locked=0] [seen_lock=1]

    unprotected read of backlog.tail but it's unclear if this value
    is depended on later.

    ====================================
    40 examples:
    /u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/tcp.c:1382:tcp_data_wait: NOTE: var <struct sock.backlog.tail> protected by <socket_lock_t.slock> [annot=first] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/tcp.c:tcp_data_wait:1382] (pop=41, s=40)
    /u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/tcp.c:1668:tcp_recvmsg: NOTE: var <struct sock.backlog.tail> protected by <socket_lock_t.slock> [annot=first] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/tcp.c:tcp_recvmsg:1668] (pop=41, s=40)
    /u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/udp.c:691:udp_sendpage: NOTE: var <struct sock.backlog.tail> protected by <socket_lock_t.slock> [annot=first] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/udp.c:udp_sendpage:691] (pop=41, s=40)
    /u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/ip_sockglue.c:688:ip_getsockopt: NOTE: var <struct sock.backlog.tail> protected by <socket_lock_t.slock> [annot=first] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/ip_sockglue.c:ip_getsockopt:688] (pop=41, s=40)
    /u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/udp.c:627:udp_sendmsg: NOTE: var <struct sock.backlog.tail> protected by <socket_lock_t.slock> [annot=first] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/udp.c:udp_sendmsg:627] (pop=41, s=40)
    /u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/ip_sockglue.c:642:ip_setsockopt: NOTE: var <struct sock.backlog.tail> protected by <socket_lock_t.slock> [annot=first] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/ip_sockglue.c:ip_setsockopt:642] (pop=41, s=40)
    -------------------------------------------------------
    BUG? pair: lock=<struct sighand_struct.siglock>, var=<struct task_struct.blocked>
    z score=-0.17
    singles = 1
    first = 3
    2 errors out of 9 uses:
    /u2/engler/mc/oses/linux/linux-2.5.62/arch/i386/kernel/signal.c:583:do_signal: ERROR: var <struct task_struct.blocked> not protected by <struct sighand_struct.siglock>(pop=9, s=7) [locked=0] [seen_lock=1]

    seems like it: other places are careful about getting
    current->blocked. here there is no lock at all:

    asmlinkage int
    sys_sigsuspend(int history0, int history1, old_sigset_t mask)
    {
    ...
    regs->eax = -EINTR;
    while (1) {
    current->state = TASK_INTERRUPTIBLE;
    schedule();
    if (do_signal(regs, &saveset))
    return -EINTR;

    ...

    // do_signal:

    if (!oldset)
    oldset = &current->blocked;

    ====================================
    7 examples:
    /u2/engler/mc/oses/linux/linux-2.5.62/kernel/signal.c:1686:sys_rt_sigprocmask: NOTE: var <struct task_struct.blocked> protected by <struct sighand_struct.siglock> [annot=single] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/kernel/signal.c:sys_rt_sigprocmask:1685] (pop=9, s=7)

    spin_lock_irq(&current->sighand->siglock);
    old_set = current->blocked;
    spin_unlock_irq(&current->sighand->siglock)

    /u2/engler/mc/oses/linux/linux-2.5.62/arch/i386/kernel/signal.c:70:sys_rt_sigsuspend: NOTE: var <struct task_struct.blocked> protected by <struct sighand_struct.siglock> [annot=first] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/arch/i386/kernel/signal.c:sys_rt_sigsuspend:69] (pop=9, s=7)
    /u2/engler/mc/oses/linux/linux-2.5.62/arch/i386/kernel/signal.c:41:sys_sigsuspend: NOTE: var <struct task_struct.blocked> protected by <struct sighand_struct.siglock> [annot=first] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/arch/i386/kernel/signal.c:sys_sigsuspend:40] (pop=9, s=7)
    /u2/engler/mc/oses/linux/linux-2.5.62/kernel/signal.c:1641:sigprocmask: NOTE: var <struct task_struct.blocked> protected by <struct sighand_struct.siglock> [annot=first] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/kernel/signal.c:sigprocmask:1640] (pop=9, s=7)
    /u2/engler/mc/oses/linux/linux-2.5.62/kernel/signal.c:1846:sys_rt_sigtimedwait: NOTE: var <struct task_struct.blocked> protected by <struct sighand_struct.siglock> [annot=none] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/kernel/signal.c:sys_rt_sigtimedwait:1844] (pop=9, s=7)
    /u2/engler/mc/oses/linux/linux-2.5.62/kernel/signal.c:1836:sys_rt_sigtimedwait: NOTE: var <struct task_struct.blocked> protected by <struct sighand_struct.siglock> [annot=none] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/kernel/signal.c:sys_rt_sigtimedwait:1824] (pop=9, s=7)
    -------------------------------------------------------
    BUG? pair: lock=<struct sighand_struct.siglock>, var=<struct task_struct.signal.group_stop_count>
    z score=-0.57
    singles = 1
    2 errors out of 7 uses:
    /u2/engler/mc/oses/linux/linux-2.5.62/kernel/signal.c:1483:get_signal_to_deliver: ERROR: var <struct task_struct.signal.group_stop_count> not protected by <struct sighand_struct.siglock>(pop=7, s=5) [locked=0] [seen_lock=1]

    seems like a race, since someone else could have slipped in and
    decremented group_stop_count after the check and before the
    acquisition:

    if (current->signal->group_stop_count > 0) {
    spin_lock_irq(&current->sighand->siglock);
    --current->signal->group_stop_count;
    spin_unlock_irq(&current->sighand->siglock
    ====================================
    5 examples:
    /u2/engler/mc/oses/linux/linux-2.5.62/kernel/signal.c:1485:get_signal_to_deliver: NOTE: var <struct task_struct.signal.group_stop_count> protected by <struct sighand_struct.siglock> [annot=single] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/kernel/signal.c:get_signal_to_deliver:1484] (pop=7, s=5)

    if (current->signal->group_stop_count > 0) {
    spin_lock_irq(&current->sighand->siglock);
    --current->signal->group_stop_count;
    spin_unlock_irq(&current->sighand->siglock

    /u2/engler/mc/oses/linux/linux-2.5.62/kernel/signal.c:207:recalc_sigpending_tsk: NOTE: var <struct task_struct.signal.group_stop_count> protected by <struct sighand_struct.siglock> [annot=none] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/kernel/exit.c:exit_notify:624
    ->/u2/engler/mc/oses/linux/linux-2.5.62/kernel/exit.c:exit_notify:631
    ->/u2/engler/mc/oses/linux/linux-2.5.62/kernel/exit.c:exit_notify:627
    ->end=/u2/engler/mc/oses/linux/linux-2.5.62/kernel/signal.c:recalc_sigpending_tsk:207] (pop=7, s=5)
    /u2/engler/mc/oses/linux/linux-2.5.62/kernel/fork.c:958:copy_process: NOTE: var <struct task_struct.signal.group_stop_count> protected by <struct sighand_struct.siglock> [annot=none] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/kernel/fork.c:copy_process:944] (pop=7, s=5)
    /u2/engler/mc/oses/linux/linux-2.5.62/kernel/signal.c:1461:get_signal_to_deliver: NOTE: var <struct task_struct.signal.group_stop_count> protected by <struct sighand_struct.siglock> [annot=none] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/kernel/signal.c:get_signal_to_deliver:1447] (pop=7, s=5)
    /u2/engler/mc/oses/linux/linux-2.5.62/kernel/fork.c:964:copy_process: NOTE: var <struct task_struct.signal.group_stop_count> protected by <struct sighand_struct.siglock> [annot=none] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/kernel/fork.c:copy_process:944] (pop=7, s=5)
    -------------------------------------------------------
    BUG? pair: lock=<&cpufreq_driver_sem:struct semaphore:1>, var=<cpufreq_driver,struct cpufreq_driver,1>
    z score=1.11
    first = 11
    global-lock
    global-var
    1 error out of 13 uses:
    /u2/engler/mc/oses/linux/linux-2.5.62/kernel/cpufreq.c:1221:cpufreq_register_driver: ERROR: var <cpufreq_driver,struct cpufreq_driver,1> not protected by <&cpufreq_driver_sem:struct semaphore:1>(pop=13, s=12) [locked=0] [seen_lock=1]

    seems like a bug --- the exmaples strongly suggest someone can make the
    driver null, in which case i believe the following is open to a race.

    if (cpufreq_driver)
    return -EBUSY;

    if (!driver_data || !driver_data->verify ||
    ((!driver_data->setpolicy) && (!driver_data->target)))
    return -EINVAL;

    down(&cpufreq_driver_sem);


    ====================================
    12 examples:
    /u2/engler/mc/oses/linux/linux-2.5.62/kernel/cpufreq.c:331:cpufreq_add_dev: NOTE: var <cpufreq_driver,struct cpufreq_driver,1> protected by <&cpufreq_driver_sem:struct semaphore:1> [annot=first] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/kernel/cpufreq.c:cpufreq_add_dev:330] (pop=13, s=12)

    down(&cpufreq_driver_sem);
    if (!cpufreq_driver) {
    up(&cpufreq_driver_sem);
    return -EINVAL;
    }


    /u2/engler/mc/oses/linux/linux-2.5.62/kernel/cpufreq.c:309:show_cpuinfo_min_freq: NOTE: var <cpufreq_driver,struct cpufreq_driver,1> protected by <&cpufreq_driver_sem:struct semaphore:1> [annot=first] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/kernel/cpufreq.c:show_cpuinfo_min_freq:309] (pop=13, s=12)
    /u2/engler/mc/oses/linux/linux-2.5.62/kernel/cpufreq.c:193:show_scaling_governor: NOTE: var <cpufreq_driver,struct cpufreq_driver,1> protected by <&cpufreq_driver_sem:struct semaphore:1> [annot=first] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/kernel/cpufreq.c:show_scaling_governor:192] (pop=13, s=12)
    /u2/engler/mc/oses/linux/linux-2.5.62/kernel/cpufreq.c:1271:cpufreq_unregister_driver: NOTE: var <cpufreq_driver,struct cpufreq_driver,1> protected by <&cpufreq_driver_sem:struct semaphore:1> [annot=first] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/kernel/cpufreq.c:cpufreq_unregister_driver:1269] (pop=13, s=12)

    down(&cpufreq_driver_sem);

    if (!cpufreq_driver ||
    ((driver != cpufreq_driver)

    /u2/engler/mc/oses/linux/linux-2.5.62/kernel/cpufreq.c:1062:cpufreq_set_policy: NOTE: var <cpufreq_driver,struct cpufreq_driver,1> protected by <&cpufreq_driver_sem:struct semaphore:1> [annot=first] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/kernel/cpufreq.c:cpufreq_set_policy:1061] (pop=13, s=12)
    /u2/engler/mc/oses/linux/linux-2.5.62/kernel/cpufreq.c:85:cpufreq_parse_governor: NOTE: var <cpufreq_driver,struct cpufreq_driver,1> protected by <&cpufreq_driver_sem:struct semaphore:1> [annot=first] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/kernel/cpufreq.c:cpufreq_parse_governor:84] (pop=13, s=12)
    -------------------------------------------------------
    BUG? pair: lock=<struct in_device.lock>, var=<struct in_device.mc_list>
    z score=-1.00
    singles = 1
    first = 4
    last = 1
    3 errors out of 9 uses:
    /u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/igmp.c:497:ip_mc_inc_group: ERROR: var <struct in_device.mc_list> not protected by <struct in_device.lock>(pop=9, s=6) [locked=0] [seen_lock=1]

    seems like they should have a read lock.


    /u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/igmp.c:544:ip_mc_dec_group: ERROR: var <struct in_device.mc_list> not protected by <struct in_device.lock>(pop=9, s=6) [locked=0] [seen_lock=1]

    read_lock?

    /u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/igmp.c:571:ip_mc_down: ERROR: var <struct in_device.mc_list> not protected by <struct in_device.lock>(pop=9, s=6) [locked=0] [seen_lock=1]
    ====================================
    6 examples:
    /u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/igmp.c:525:ip_mc_inc_group: NOTE: var <struct in_device.mc_list> protected by <struct in_device.lock> [annot=single] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/igmp.c:ip_mc_inc_group:523] (pop=9, s=6)

    write_lock_bh(&in_dev->lock);
    im->next=in_dev->mc_list;
    in_dev->mc_list=im;
    write_unlock_bh(&in_dev->lock);


    /u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/igmp.c:602:ip_mc_destroy_dev: NOTE: var <struct in_device.mc_list> protected by <struct in_device.lock> [annot=first] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/igmp.c:ip_mc_destroy_dev:601] (pop=9, s=6)

    write_lock_bh(&in_dev->lock);
    while ((i = in_dev->mc_list) != NULL) {


    /u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/igmp.c:773:ip_check_mc: NOTE: var <struct in_device.mc_list> protected by <struct in_device.lock> [annot=first] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/igmp.c:ip_check_mc:772] (pop=9, s=6)


    read_lock(&in_dev->lock);
    for (im=in_dev->mc_list; im; im=im->next) {
    if (im->multiaddr == mc_addr) {
    read_unlock(&in_dev->lock);

    -------------------------------------------------------
    BUG? pair: lock=<&fib_rules_lock:rwlock_t:1>, var=<struct fib_rule.r_ifindex>
    z score=-1.12
    singles = 1
    last = 1
    global-lock
    2 errors out of 5 uses:
    /u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/fib_rules.c:289:fib_rules_detach: ERROR: var <struct fib_rule.r_ifindex> not protected by <&fib_rules_lock:rwlock_t:1>(pop=5, s=3) [locked=0] [seen_lock=1]

    this seems pretty busted: they check r->r_ifindex and then
    write to it without rechecking that it's the same value:

    for (r=fib_rules; r; r=r->r_next) {
    if (r->r_ifindex == dev->ifindex) {
    write_lock_bh(&fib_rules_lock);
    r->r_ifindex = -1;
    write_unlock_bh(&fib_rules_lock);
    }
    }
    /u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/fib_rules.c:302:fib_rules_attach: ERROR: var <struct fib_rule.r_ifindex> not protected by <&fib_rules_lock:rwlock_t:1>(pop=5, s=3) [locked=0] [seen_lock=1]

    same: check, and a write without rechecking:

    for (r=fib_rules; r; r=r->r_next) {
    if (r->r_ifindex == -1 && strcmp(dev->name, r->r_ifname) == 0) {
    write_lock_bh(&fib_rules_lock);
    r->r_ifindex = dev->ifindex;
    write_unlock_bh(&fib_rules_lock);

    ====================================
    3 examples:
    /u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/fib_rules.c:291:fib_rules_detach: NOTE: var <struct fib_rule.r_ifindex> protected by <&fib_rules_lock:rwlock_t:1> [annot=single] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/fib_rules.c:fib_rules_detach:290] (pop=5, s=3)
    /u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/fib_rules.c:304:fib_rules_attach: NOTE: var <struct fib_rule.r_ifindex> protected by <&fib_rules_lock:rwlock_t:1> [annot=last] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/fib_rules.c:fib_rules_attach:303] (pop=5, s=3)
    /u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/fib_rules.c:323:fib_lookup: NOTE: var <struct fib_rule.r_ifindex> protected by <&fib_rules_lock:rwlock_t:1> [annot=none] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/fib_rules.c:fib_lookup:321] (pop=5, s=3)
    -------------------------------------------------------
    BUG? pair: lock=<&fib_rules_lock:rwlock_t:1>, var=<*rp,struct fib_rule,0>
    z score=-1.50
    singles = 1
    global-lock
    2 errors out of 4 uses:
    /u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/fib_rules.c:111:inet_rtm_delrule: ERROR: var <*rp,struct fib_rule,0> not protected by <&fib_rules_lock:rwlock_t:1>(pop=4, s=2) [locked=0] [seen_lock=1]
    /u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/fib_rules.c:234:inet_rtm_newrule: ERROR: var <*rp,struct fib_rule,0> not protected by <&fib_rules_lock:rwlock_t:1>(pop=4, s=2) [locked=0] [seen_lock=1]

    sure seems like the code is depending on state from outside the
    critical section:

    while ( (r = *rp) != NULL ) {
    if (r->r_preference > new_r->r_preference)
    break;
    rp = &r->r_next;
    }

    new_r->r_next = r;
    atomic_inc(&new_r->r_clntref);
    write_lock_bh(&fib_rules_lock);
    *rp = new_r;
    write_unlock_bh(&fib_rules_lock);

    ====================================
    2 examples:
    /u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/fib_rules.c:243:inet_rtm_newrule: NOTE: var <*rp,struct fib_rule,0> protected by <&fib_rules_lock:rwlock_t:1> [annot=single] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/fib_rules.c:inet_rtm_newrule:242] (pop=4, s=2)
    /u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/fib_rules.c:129:inet_rtm_delrule: NOTE: var <*rp,struct fib_rule,0> protected by <&fib_rules_lock:rwlock_t:1> [annot=none] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/fib_rules.c:inet_rtm_delrule:128] (pop=4, s=2)

    write_lock_bh(&fib_rules_lock);
    *rp = r->r_next;
    r->r_dead = 1;
    write_unlock_bh(&fib_rules_lock);

    -------------------------------------------------------
    MINOR: not false, just dumb pair: lock=<&exec_domains_lock:rwlock_t:1>, var=<exec_domains,struct exec_domain,1>
    z score=0.20
    first = 5
    global-lock
    global-var
    1 error out of 6 uses:
    /u2/engler/mc/oses/linux/linux-2.5.62/kernel/exec_domain.c:143:unregister_exec_domain: ERROR: var <exec_domains,struct exec_domain,1> not protected by <&exec_domains_lock:rwlock_t:1>(pop=6, s=5) [locked=0] [seen_lock=1]

    epp = &exec_domains;
    write_lock(&exec_domains_lock);
    for (epp = &exec_domains; *epp; epp = &(*epp)->next) {

    ====================================
    5 examples:
    /u2/engler/mc/oses/linux/linux-2.5.62/kernel/exec_domain.c:98:lookup_exec_domain: NOTE: var <exec_domains,struct exec_domain,1> protected by <&exec_domains_lock:rwlock_t:1> [annot=first] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/kernel/exec_domain.c:lookup_exec_domain:96] (pop=6, s=5)

    read_lock(&exec_domains_lock);

    for (ep = exec_domains; ep; ep = ep->next) {
    if (pers >= ep->pers_low && pers <= ep->pers_high)
    if (try_module_get(ep->module))
    goto out;

    /u2/engler/mc/oses/linux/linux-2.5.62/kernel/exec_domain.c:208:get_exec_domain_list: NOTE: var <exec_domains,struct exec_domain,1> protected by <&exec_domains_lock:rwlock_t:1> [annot=first] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/kernel/exec_domain.c:get_exec_domain_list:207] (pop=6, s=5)

    read_lock(&exec_domains_lock);
    for (ep = exec_domains; ep && len < PAGE_SIZE - 80; ep = ep->next)
    len += sprintf(page + len, "%d-%d\t%-16s\t[%s]\n",
    ep->pers_low, ep->pers_high, ep->name,

    /u2/engler/mc/oses/linux/linux-2.5.62/kernel/exec_domain.c:145:unregister_exec_domain: NOTE: var <exec_domains,struct exec_domain,1> protected by <&exec_domains_lock:rwlock_t:1> [annot=first] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/kernel/exec_domain.c:unregister_exec_domain:144] (pop=6, s=5)
    /u2/engler/mc/oses/linux/linux-2.5.62/kernel/exec_domain.c:83:lookup_exec_domain: NOTE: var <exec_domains,struct exec_domain,1> protected by <&exec_domains_lock:rwlock_t:1> [annot=first] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/kernel/exec_domain.c:lookup_exec_domain:82] (pop=6, s=5)
    /u2/engler/mc/oses/linux/linux-2.5.62/kernel/exec_domain.c:124:register_exec_domain: NOTE: var <exec_domains,struct exec_domain,1> protected by <&exec_domains_lock:rwlock_t:1> [annot=first] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/kernel/exec_domain.c:register_exec_domain:123] (pop=6, s=5)
    -------------------------------------------------------
    BUG? pair: lock=<&logbuf_lock:spinlock_t:1>, var=<log_start,unsigned int,1>
    z score=-0.57
    first = 3
    last = 1
    global-lock
    global-var
    2 errors out of 7 uses:
    /u2/engler/mc/oses/linux/linux-2.5.62/kernel/printk.c:179:do_syslog: ERROR: var <log_start,unsigned int,1> not protected by <&logbuf_lock:spinlock_t:1>(pop=7, s=5) [locked=0] [seen_lock=1]

    supposed to protect log start?

    ====================================
    5 examples:
    /u2/engler/mc/oses/linux/linux-2.5.62/kernel/printk.c:625:register_console: NOTE: var <log_start,unsigned int,1> protected by <&logbuf_lock:spinlock_t:1> [annot=first] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/kernel/printk.c:register_console:624] (pop=7, s=5)

    spin_lock_irqsave(&logbuf_lock, flags);
    con_start = log_start;
    spin_unlock_irqrestore(&logbuf_lock, flags);

    /u2/engler/mc/oses/linux/linux-2.5.62/kernel/printk.c:184:do_syslog: NOTE: var <log_start,unsigned int,1> protected by <&logbuf_lock:spinlock_t:1> [annot=first] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/kernel/printk.c:do_syslog:183] (pop=7, s=5)
    /u2/engler/mc/oses/linux/linux-2.5.62/kernel/printk.c:498:release_console_sem: NOTE: var <log_start,unsigned int,1> protected by <&logbuf_lock:spinlock_t:1> [annot=first] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/kernel/printk.c:release_console_sem:497] (pop=7, s=5)
    /u2/engler/mc/oses/linux/linux-2.5.62/kernel/printk.c:186:do_syslog: NOTE: var <log_start,unsigned int,1> protected by <&logbuf_lock:spinlock_t:1> [annot=last] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/kernel/printk.c:do_syslog:183] (pop=7, s=5)
    /u2/engler/mc/oses/linux/linux-2.5.62/kernel/printk.c:365:emit_log_char: NOTE: var <log_start,unsigned int,1> protected by <&logbuf_lock:spinlock_t:1> [annot=none] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/kernel/printk.c:printk:403
    ->/u2/engler/mc/oses/linux/linux-2.5.62/kernel/printk.c:printk:423
    ->end=/u2/engler/mc/oses/linux/linux-2.5.62/kernel/printk.c:emit_log_char:365] (pop=7, s=5)
    -------------------------------------------------------
    BUG? pair: lock=<struct shmem_inode_info.lock>, var=<struct shmem_inode_info.next_index>
    z score=0.20
    first = 2
    1 error out of 6 uses:
    /u2/engler/mc/oses/linux/linux-2.5.62/mm/shmem.c:385:shmem_truncate: ERROR: var <struct shmem_inode_info.next_index> not protected by <struct shmem_inode_info.lock>(pop=6, s=5) [locked=0] [seen_lock=1]

    seems like a potential race, since info_next_index seems like it could
    get decreased in the meantime violating the if-stmt:

    if (idx >= info->next_index)
    return;

    spin_lock(&info->lock);
    limit = info->next_index;


    ====================================
    5 examples:
    /u2/engler/mc/oses/linux/linux-2.5.62/mm/shmem.c:389:shmem_truncate: NOTE: var <struct shmem_inode_info.next_index> protected by <struct shmem_inode_info.lock> [annot=first] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/mm/shmem.c:shmem_truncate:388] (pop=6, s=5)
    /u2/engler/mc/oses/linux/linux-2.5.62/mm/shmem.c:582:shmem_unuse_inode: NOTE: var <struct shmem_inode_info.next_index> protected by <struct shmem_inode_info.lock> [annot=first] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/mm/shmem.c:shmem_unuse_inode:581] (pop=6, s=5)
    /u2/engler/mc/oses/linux/linux-2.5.62/mm/shmem.c:482:shmem_truncate: NOTE: var <struct shmem_inode_info.next_index> protected by <struct shmem_inode_info.lock> [annot=none] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/mm/shmem.c:shmem_truncate:388] (pop=6, s=5)
    /u2/engler/mc/oses/linux/linux-2.5.62/mm/shmem.c:335:shmem_swp_alloc: NOTE: var <struct shmem_inode_info.next_index> protected by <struct shmem_inode_info.lock> [annot=none] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/mm/shmem.c:shmem_swp_alloc:324] (pop=6, s=5)
    /u2/engler/mc/oses/linux/linux-2.5.62/mm/shmem.c:343:shmem_swp_alloc: NOTE: var <struct shmem_inode_info.next_index> protected by <struct shmem_inode_info.lock> [annot=none] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/mm/shmem.c:shmem_getpage:755
    ->/u2/engler/mc/oses/linux/linux-2.5.62/mm/shmem.c:shmem_getpage:757
    ->end=/u2/engler/mc/oses/linux/linux-2.5.62/mm/shmem.c:shmem_swp_alloc:343] (pop=6, s=5)
    -------------------------------------------------------
    BUG: pair: lock=<struct ipq.lock>, var=<struct ipq.last_in>
    z score=-0.57
    first = 2
    2 errors out of 7 uses:
    /u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/ip_fragment.c:163:ip_frag_destroy: ERROR: var <struct ipq.last_in> not protected by <struct ipq.lock>(pop=7, s=5) [locked=0] [seen_lock=1]

    BUG_ON call that looks at last_in

    /u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/ip_fragment.c:289:ip_frag_intern: ERROR: var <struct ipq.last_in> not protected by <struct ipq.lock>(pop=7, s=5) [locked=0] [seen_lock=1]

    seems like a definite bug they read-modify-write it right after
    releasing the lock:

    write_unlock(&ipfrag_lock);
    qp_in->last_in |= COMPLETE;
    ipq_put(qp_in);

    ====================================
    5 examples:
    /u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/ip_fragment.c:226:ip_evictor: NOTE: var <struct ipq.last_in> protected by <struct ipq.lock> [annot=first] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/ip_fragment.c:ip_evictor:225] (pop=7, s=5)

    spin_lock(&qp->lock);
    if (!(qp->last_in&COMPLETE))
    ipq_kill(qp);
    spin_unlock(&qp->lock);

    /u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/ip_fragment.c:249:ip_expire: NOTE: var <struct ipq.last_in> protected by <struct ipq.lock> [annot=first] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/ip_fragment.c:ip_expire:247] (pop=7, s=5)

    spin_lock(&qp->lock);

    if (qp->last_in & COMPLETE)
    goto out;

    /u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/ip_fragment.c:619:ip_defrag: NOTE: var <struct ipq.last_in> protected by <struct ipq.lock> [annot=none] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/ip_fragment.c:ip_defrag:615] (pop=7, s=5)
    /u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/ip_fragment.c:377:ip_frag_queue: NOTE: var <struct ipq.last_in> protected by <struct ipq.lock> [annot=none] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/ip_fragment.c:ip_defrag:615
    ->/u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/ip_fragment.c:ip_defrag:617
    ->end=/u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/ip_fragment.c:ip_frag_queue:377] (pop=7, s=5)
    /u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/ip_fragment.c:193:ipq_kill: NOTE: var <struct ipq.last_in> protected by <struct ipq.lock> [annot=none] [level=0] [path=/u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/ip_fragment.c:ip_defrag:615
    ->/u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/ip_fragment.c:ip_defrag:623
    ->/u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/ip_fragment.c:ip_defrag:623
    ->/u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/ip_fragment.c:ip_defrag:621
    ->/u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/ip_fragment.c:ip_frag_reasm:515
    ->end=/u2/engler/mc/oses/linux/linux-2.5.62/net/ipv4/ip_fragment.c:ipq_kill:193] (pop=7, s=5)
    -------------------------------------------------------
    -
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