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    Subject[PATCH] sigaction should clear all signals on SIG_IGN, not just < 32
    While rooting aroung in the signal code trying to understand how to
    fix the SIG_IGN ploy (set sig handler to SIG_IGN and flood system with
    high speed repeating timers) I came across what, I think, is a problem
    in sigaction() in that when processing a SIG_IGN request it flushes
    signals from 1 to SIGRTMIN and leaves the rest. The attached patch is
    an attempt to fix this.

    --
    George Anzinger george@mvista.com
    HRT (High-res-timers): http://sourceforge.net/projects/high-res-timers/

    Source: MontaVista Software, Inc.
    Type: Defect Fix
    Description:
    It appeares that the sigaction system call, when processing a SIG_IGN or
    a SIG_DFL, is removing only signals that appear in the first mask word.

    Signed-off-by: George Anzinger <george@mvista.com>

    include/linux/signal.h | 16 ++++++++++++++++
    kernel/signal.c | 34 ++++++++++++++++++++++++++++++++--
    2 files changed, 48 insertions(+), 2 deletions(-)

    Index: linux-2.6.15-rc/kernel/signal.c
    ===================================================================
    --- linux-2.6.15-rc.orig/kernel/signal.c
    +++ linux-2.6.15-rc/kernel/signal.c
    @@ -633,6 +633,33 @@ void signal_wake_up(struct task_struct *
    * Returns 1 if any signals were found.
    *
    * All callers must be holding the siglock.
    + *
    + * This version takes a sigset mask and looks at all signals,
    + * not just those in the first mask word.
    + */
    +static int rm_from_queue_full(sigset_t *mask, struct sigpending *s)
    +{
    + struct sigqueue *q, *n;
    + sigset_t m;
    +
    + sigandsets(&m, mask, &s->signal);
    + if (sigisemptyset(&m))
    + return 0;
    +
    + signandsets(&s->signal, &s->signal, mask);
    + list_for_each_entry_safe(q, n, &s->list, list) {
    + if (sigismember(mask, q->info.si_signo)) {
    + list_del_init(&q->list);
    + __sigqueue_free(q);
    + }
    + }
    + return 1;
    +}
    +/*
    + * Remove signals in mask from the pending set and queue.
    + * Returns 1 if any signals were found.
    + *
    + * All callers must be holding the siglock.
    */
    static int rm_from_queue(unsigned long mask, struct sigpending *s)
    {
    @@ -2471,6 +2498,7 @@ int
    do_sigaction(int sig, const struct k_sigaction *act, struct k_sigaction *oact)
    {
    struct k_sigaction *k;
    + sigset_t mask;

    if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
    return -EINVAL;
    @@ -2518,9 +2546,11 @@ do_sigaction(int sig, const struct k_sig
    *k = *act;
    sigdelsetmask(&k->sa.sa_mask,
    sigmask(SIGKILL) | sigmask(SIGSTOP));
    - rm_from_queue(sigmask(sig), &t->signal->shared_pending);
    + sigemptyset(&mask);
    + sigaddset(&mask, sig);
    + rm_from_queue_full(&mask, &t->signal->shared_pending);
    do {
    - rm_from_queue(sigmask(sig), &t->pending);
    + rm_from_queue_full(&mask, &t->pending);
    recalc_sigpending_tsk(t);
    t = next_thread(t);
    } while (t != current);
    Index: linux-2.6.15-rc/include/linux/signal.h
    ===================================================================
    --- linux-2.6.15-rc.orig/include/linux/signal.h
    +++ linux-2.6.15-rc/include/linux/signal.h
    @@ -82,6 +82,22 @@ static inline int sigfindinword(unsigned

    #endif /* __HAVE_ARCH_SIG_BITOPS */

    +static inline int sigisemptyset(sigset_t *set)
    +{
    + extern void _NSIG_WORDS_is_unsupported_size(void);
    + switch (_NSIG_WORDS) {
    + case 4:
    + return (set->sig[3] | set->sig[2] |
    + set->sig[1] | set->sig[0]) == 0;
    + case 2:
    + return (set->sig[1] | set->sig[0]) == 0;
    + case 1:
    + return set->sig[0] == 0;
    + default:
    + _NSIG_WORDS_is_unsupported_size();
    + }
    +}
    +
    #define sigmask(sig) (1UL << ((sig) - 1))

    #ifndef __HAVE_ARCH_SIG_SETOPS
    \
     
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      Last update: 2005-11-17 00:29    [W:0.026 / U:59.028 seconds]
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