1 files changed, 47 insertions, 26 deletions

diff --git a/kernel/signal.c b/kernel/signal.c
index 1814e68e4de3..dbd7fe073c55 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -159,6 +159,10 @@ void recalc_sigpending(void)
 
 /* Given the mask, find the first available signal that should be serviced. */
 
+#define SYNCHRONOUS_MASK \
+        (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
+         sigmask(SIGTRAP) | sigmask(SIGFPE))
+
 int next_signal(struct sigpending *pending, sigset_t *mask)
 {
         unsigned long i, *s, *m, x;
@@ -166,26 +170,39 @@ int next_signal(struct sigpending *pending, sigset_t *mask)
 
         s = pending->signal.sig;
         m = mask->sig;
+
+        /*
+         * Handle the first word specially: it contains the
+         * synchronous signals that need to be dequeued first.
+         */
+        x = *s &~ *m;
+        if (x) {
+                if (x & SYNCHRONOUS_MASK)
+                        x &= SYNCHRONOUS_MASK;
+                sig = ffz(~x) + 1;
+                return sig;
+        }
+
         switch (_NSIG_WORDS) {
         default:
-                for (i = 0; i < _NSIG_WORDS; ++i, ++s, ++m)
-                        if ((x = *s &~ *m) != 0) {
-                                sig = ffz(~x) + i*_NSIG_BPW + 1;
-                                break;
-                        }
+                for (i = 1; i < _NSIG_WORDS; ++i) {
+                        x = *++s &~ *++m;
+                        if (!x)
+                                continue;
+                        sig = ffz(~x) + i*_NSIG_BPW + 1;
+                        break;
+                }
                 break;
 
-        case 2: if ((x = s[0] &~ m[0]) != 0)
-                        sig = 1;
-                else if ((x = s[1] &~ m[1]) != 0)
-                        sig = _NSIG_BPW + 1;
-                else
+        case 2:
+                x = s[1] &~ m[1];
+                if (!x)
                         break;
-                sig += ffz(~x);
+                sig = ffz(~x) + _NSIG_BPW + 1;
                 break;
 
-        case 1: if ((x = *s &~ *m) != 0)
-                        sig = ffz(~x) + 1;
+        case 1:
+                /* Nothing to do */
                 break;
         }
 
@@ -218,17 +235,17 @@ __sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimi
         struct user_struct *user;
 
         /*
-         * We won't get problems with the target's UID changing under us
-         * because changing it requires RCU be used, and if t != current, the
-         * caller must be holding the RCU readlock (by way of a spinlock) and
-         * we use RCU protection here
+         * Protect access to @t credentials. This can go away when all
+         * callers hold rcu read lock.
          */
+        rcu_read_lock();
         user = get_uid(__task_cred(t)->user);
         atomic_inc(&user->sigpending);
+        rcu_read_unlock();
 
         if (override_rlimit ||
             atomic_read(&user->sigpending) <=
-                        t->signal->rlim[RLIMIT_SIGPENDING].rlim_cur) {
+                        task_rlimit(t, RLIMIT_SIGPENDING)) {
                 q = kmem_cache_alloc(sigqueue_cachep, flags);
         } else {
                 print_dropped_signal(sig);
@@ -979,7 +996,8 @@ static void print_fatal_signal(struct pt_regs *regs, int signr)
                 for (i = 0; i < 16; i++) {
                         unsigned char insn;
 
-                        __get_user(insn, (unsigned char *)(regs->ip + i));
+                        if (get_user(insn, (unsigned char *)(regs->ip + i)))
+                                break;
                         printk("%02x ", insn);
                 }
         }
@@ -1179,11 +1197,12 @@ int kill_pid_info_as_uid(int sig, struct siginfo *info, struct pid *pid,
         int ret = -EINVAL;
         struct task_struct *p;
         const struct cred *pcred;
+        unsigned long flags;
 
         if (!valid_signal(sig))
                 return ret;
 
-        read_lock(&tasklist_lock);
+        rcu_read_lock();
         p = pid_task(pid, PIDTYPE_PID);
         if (!p) {
                 ret = -ESRCH;
@@ -1199,14 +1218,16 @@ int kill_pid_info_as_uid(int sig, struct siginfo *info, struct pid *pid,
         ret = security_task_kill(p, info, sig, secid);
         if (ret)
                 goto out_unlock;
-        if (sig && p->sighand) {
-                unsigned long flags;
-                spin_lock_irqsave(&p->sighand->siglock, flags);
-                ret = __send_signal(sig, info, p, 1, 0);
-                spin_unlock_irqrestore(&p->sighand->siglock, flags);
+
+        if (sig) {
+                if (lock_task_sighand(p, &flags)) {
+                        ret = __send_signal(sig, info, p, 1, 0);
+                        unlock_task_sighand(p, &flags);
+                } else
+                        ret = -ESRCH;
         }
 out_unlock:
-        read_unlock(&tasklist_lock);
+        rcu_read_unlock();
         return ret;
 }
 EXPORT_SYMBOL_GPL(kill_pid_info_as_uid);