signal: Only handle on NSIG signals on signal functions (BZ #25657)

The upper bits of the sigset_t s not fully initialized in the signal
mask calls that return information from kernel (sigprocmask,
sigpending, and pthread_sigmask), since the exported sigset_t size
(1024 bits) is larger than Linux support one (64 or 128 bits).
It might make sigisemptyset/sigorset/sigandset fail if the mask
is filled prior the call.

This patch changes the internal signal function to handle up to
supported Linux signal number (_NSIG), the remaining bits are
untouched.

Checked on x86_64-linux-gnu and i686-linux-gnu.

nptl/Makefile

@@ -293,7 +293,7 @@ tests = tst-attr2 tst-attr3 tst-default-attr \
 	tst-cleanup0 tst-cleanup1 tst-cleanup2 tst-cleanup3 tst-cleanup4 \
 	tst-flock1 tst-flock2 \
 	tst-signal1 tst-signal2 tst-signal3 tst-signal4 tst-signal5 \
-	tst-signal6 \
+	tst-signal6 tst-signal8 \
 	tst-exec1 tst-exec2 tst-exec3 tst-exec4 tst-exec5 \
 	tst-exit1 tst-exit2 tst-exit3 \
 	tst-stdio1 tst-stdio2 \

nptl/pthread_sigmask.c

@@ -29,12 +29,11 @@ __pthread_sigmask (int how, const sigset_t *newmask, sigset_t *oldmask)
   /* The only thing we have to make sure here is that SIGCANCEL and
      SIGSETXID is not blocked.  */
   if (newmask != NULL
-      && (__builtin_expect (__sigismember (newmask, SIGCANCEL), 0)
+      && (__glibc_unlikely (__sigismember (newmask, SIGCANCEL))
-	  || __builtin_expect (__sigismember (newmask, SIGSETXID), 0)))
+         || __glibc_unlikely (__sigismember (newmask, SIGSETXID))))
     {
       local_newmask = *newmask;
-      __sigdelset (&local_newmask, SIGCANCEL);
+      __clear_internal_signals (&local_newmask);
-      __sigdelset (&local_newmask, SIGSETXID);
       newmask = &local_newmask;
     }
 

nptl/tst-signal8.c

@@ -0,0 +1,62 @@
+/* Tests for sigisemptyset and pthread_sigmask.
+   Copyright (C) 2020 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <signal.h>
+
+#include <support/check.h>
+#include <support/xthread.h>
+
+static void *
+tf (void *arg)
+{
+  {
+    sigset_t set;
+    sigemptyset (&set);
+    TEST_COMPARE (pthread_sigmask (SIG_BLOCK, 0, &set), 0);
+    TEST_COMPARE (sigisemptyset (&set), 1);
+  }
+
+  {
+    sigset_t set;
+    sigfillset (&set);
+    TEST_COMPARE (pthread_sigmask (SIG_BLOCK, 0, &set), 0);
+    TEST_COMPARE (sigisemptyset (&set), 1);
+  }
+
+  return NULL;
+}
+
+static int
+do_test (void)
+{
+  /* Ensure current SIG_BLOCK mask empty.  */
+  {
+    sigset_t set;
+    sigemptyset (&set);
+    TEST_COMPARE (sigprocmask (SIG_BLOCK, &set, 0), 0);
+  }
+
+  {
+    pthread_t thr = xpthread_create (NULL, tf, NULL);
+    xpthread_join (thr);
+  }
+
+  return 0;
+}
+
+#include <support/test-driver.c>

signal/Makefile

@@ -49,6 +49,7 @@ tests		:= tst-signal tst-sigset tst-sigsimple tst-raise tst-sigset2 \
 		   tst-sigwait-eintr tst-sigaction \
 		   tst-minsigstksz-1 tst-minsigstksz-2 tst-minsigstksz-3 \
 		   tst-minsigstksz-3a tst-minsigstksz-4 \
+		   tst-sigisemptyset
 
 include ../Rules
 

signal/sigsetops.c

@@ -26,28 +26,28 @@
 
 int
 attribute_compat_text_section
-(__sigismember) (const __sigset_t *set, int sig)
+__sigismember_compat (const __sigset_t *set, int sig)
 {
   return __sigismember (set, sig);
 }
-compat_symbol (libc, __sigismember, __sigismember, GLIBC_2_0);
+compat_symbol (libc, __sigismember_compat, __sigismember, GLIBC_2_0);
 
 int
 attribute_compat_text_section
-(__sigaddset) (__sigset_t *set, int sig)
+__sigaddset_compat (__sigset_t *set, int sig)
 {
   __sigaddset (set, sig);
   return 0;
 }
-compat_symbol (libc, __sigaddset, __sigaddset, GLIBC_2_0);
+compat_symbol (libc, __sigaddset_compat, __sigaddset, GLIBC_2_0);
 
 int
 attribute_compat_text_section
-(__sigdelset) (__sigset_t *set, int sig)
+__sigdelset_compat (__sigset_t *set, int sig)
 {
   __sigdelset (set, sig);
   return 0;
 }
-compat_symbol (libc, __sigdelset, __sigdelset, GLIBC_2_0);
+compat_symbol (libc, __sigdelset_compat, __sigdelset, GLIBC_2_0);
 
 #endif

signal/tst-sigisemptyset.c

@@ -0,0 +1,95 @@
+/* Tests for sigisemptyset/sigorset/sigandset.
+   Copyright (C) 2020 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <signal.h>
+
+#include <support/check.h>
+
+static int
+do_test (void)
+{
+  {
+    sigset_t set;
+    sigemptyset (&set);
+    TEST_COMPARE (sigisemptyset (&set), 1);
+  }
+
+  {
+    sigset_t set;
+    sigfillset (&set);
+    TEST_COMPARE (sigisemptyset (&set), 0);
+  }
+
+  {
+    sigset_t setfill, setempty, set;
+    sigfillset (&setfill);
+    sigemptyset (&setempty);
+
+    sigorset (&set, &setfill, &setempty);
+    TEST_COMPARE (sigisemptyset (&set), 0);
+
+    sigandset (&set, &setfill, &setempty);
+    TEST_COMPARE (sigisemptyset (&set), 1);
+  }
+
+  /* Ensure current SIG_BLOCK mask empty.  */
+  {
+    sigset_t set;
+    sigemptyset (&set);
+    TEST_COMPARE (sigprocmask (SIG_BLOCK, &set, 0), 0);
+  }
+
+  {
+    sigset_t set;
+    sigemptyset (&set);
+    TEST_COMPARE (sigprocmask (SIG_BLOCK, 0, &set), 0);
+    TEST_COMPARE (sigisemptyset (&set), 1);
+  }
+
+  {
+    sigset_t set;
+    sigfillset (&set);
+    TEST_COMPARE (sigprocmask (SIG_BLOCK, 0, &set), 0);
+    TEST_COMPARE (sigisemptyset (&set), 1);
+  }
+
+  /* Block all signals.  */
+  {
+    sigset_t set;
+    sigfillset (&set);
+    TEST_COMPARE (sigprocmask (SIG_BLOCK, &set, 0), 0);
+  }
+
+  {
+    sigset_t set;
+    sigemptyset (&set);
+    TEST_COMPARE (sigpending (&set), 0);
+    TEST_COMPARE (sigisemptyset (&set), 1);
+  }
+
+  {
+    sigset_t set;
+    sigfillset (&set);
+    TEST_COMPARE (sigpending (&set), 0);
+    TEST_COMPARE (sigisemptyset (&set), 1);
+  }
+
+  return 0;
+}
+
+#include <support/test-driver.c>

sysdeps/unix/sysv/linux/sigpending.c

@@ -15,13 +15,9 @@
    License along with the GNU C Library; if not, see
    <https://www.gnu.org/licenses/>.  */
 
-#include <errno.h>
 #include <signal.h>
-#include <unistd.h>
-
 #include <sysdep.h>
-#include <sys/syscall.h>
+#include <sigsetops.h>
-
 
 /* Change the set of blocked signals to SET,
    wait until a signal arrives, and restore the set of blocked signals.  */

sysdeps/unix/sysv/linux/sigsetops.h

@@ -26,83 +26,82 @@
   (((unsigned long int) 1) << (((sig) - 1) % (8 * sizeof (unsigned long int))))
 
 /* Return the word index for SIG.  */
-# define __sigword(sig) (((sig) - 1) / (8 * sizeof (unsigned long int)))
+static inline unsigned long int
+__sigword (int sig)
+{
+  return (sig - 1) / (8 * sizeof (unsigned long int));
+}
 
-# define __sigemptyset(set)					\
+/* Linux sig* functions only handle up to __NSIG_WORDS words instead of
-  (__extension__ ({						\
+   full _SIGSET_NWORDS sigset size.  The signal numbers are 1-based, and
-    int __cnt = _SIGSET_NWORDS;					\
+   bit 0 of a signal mask is for signal 1.  */
-    sigset_t *__set = (set);					\
-    while (--__cnt >= 0)					\
-      __set->__val[__cnt] = 0;					\
-    (void)0;							\
-  }))
 
-# define __sigfillset(set)					\
+# define __NSIG_WORDS (_NSIG / (8 * sizeof (unsigned long int )))
-  (__extension__ ({						\
-    int __cnt = _SIGSET_NWORDS;					\
-    sigset_t *__set = (set);					\
-    while (--__cnt >= 0)					\
-      __set->__val[__cnt] = ~0UL;				\
-    (void)0;							\
-  }))
 
-# define __sigisemptyset(set)					\
+static inline void
-  (__extension__ ({						\
+__sigemptyset (sigset_t *set)
-    int __cnt = _SIGSET_NWORDS;					\
+{
-    const sigset_t *__set = (set);				\
+  int cnt = __NSIG_WORDS;
-    int __ret = __set->__val[--__cnt];				\
+  while (--cnt >= 0)
-    while (!__ret && --__cnt >= 0)				\
+   set->__val[cnt] = 0;
-      __ret = __set->__val[__cnt];				\
+}
-    __ret == 0;							\
-  }))
 
-# define __sigandset(dest, left, right)				\
+static inline void
-  (__extension__ ({						\
+__sigfillset (sigset_t *set)
-    int __cnt = _SIGSET_NWORDS;					\
+{
-    sigset_t *__dest = (dest);					\
+  int cnt = __NSIG_WORDS;
-    const sigset_t *__left = (left);				\
+  while (--cnt >= 0)
-    const sigset_t *__right = (right);				\
+   set->__val[cnt] = ~0UL;
-    while (--__cnt >= 0)					\
+}
-      __dest->__val[__cnt] = (__left->__val[__cnt]		\
-			      & __right->__val[__cnt]);		\
-    (void)0;							\
-  }))
 
-# define __sigorset(dest, left, right)				\
+static inline int
-  (__extension__ ({						\
+__sigisemptyset (const sigset_t *set)
-    int __cnt = _SIGSET_NWORDS;					\
+{
-    sigset_t *__dest = (dest);					\
+  int cnt = __NSIG_WORDS;
-    const sigset_t *__left = (left);				\
+  int ret = set->__val[--cnt];
-    const sigset_t *__right = (right);				\
+  while (ret == 0 && --cnt >= 0)
-    while (--__cnt >= 0)					\
+    ret = set->__val[cnt];
-      __dest->__val[__cnt] = (__left->__val[__cnt]		\
+  return ret == 0;
-			      | __right->__val[__cnt]);		\
+}
-    (void)0;							\
-  }))
 
-/* These macros needn't check for a bogus signal number;
+static inline void
-   error checking is done in the non-__ versions.  */
+__sigandset (sigset_t *dest, const sigset_t *left, const sigset_t *right)
-# define __sigismember(set, sig)				\
+{
-  (__extension__ ({						\
+  int cnt = __NSIG_WORDS;
-    unsigned long int __mask = __sigmask (sig);			\
+  while (--cnt >= 0)
-    unsigned long int __word = __sigword (sig);			\
+    dest->__val[cnt] = left->__val[cnt] & right->__val[cnt];
-    (set)->__val[__word] & __mask ? 1 : 0;			\
+}
-  }))
 
-# define __sigaddset(set, sig)					\
+static inline void
-  (__extension__ ({						\
+__sigorset (sigset_t *dest, const sigset_t *left, const sigset_t *right)
-    unsigned long int __mask = __sigmask (sig);			\
+{
-    unsigned long int __word = __sigword (sig);			\
+  int cnt = __NSIG_WORDS;
-    (set)->__val[__word] |= __mask;				\
+  while (--cnt >= 0)
-    (void)0;							\
+    dest->__val[cnt] = left->__val[cnt] | right->__val[cnt];
-  }))
+}
 
-# define __sigdelset(set, sig)					\
+static inline int
-  (__extension__ ({						\
+__sigismember (const sigset_t *set, int sig)
-    unsigned long int __mask = __sigmask (sig);			\
+{
-    unsigned long int __word = __sigword (sig);			\
+  unsigned long int mask = __sigmask (sig);
-    (set)->__val[__word] &= ~__mask;				\
+  unsigned long int word = __sigword (sig);
-    (void)0;							\
+  return set->__val[word] & mask ? 1 : 0;
- }))
+}
+
+static inline void
+__sigaddset (sigset_t *set, int sig)
+{
+  unsigned long int mask = __sigmask (sig);
+  unsigned long int word = __sigword (sig);
+  set->__val[word] |= mask;
+}
+
+static inline void
+__sigdelset (sigset_t *set, int sig)
+{
+  unsigned long int mask = __sigmask (sig);
+  unsigned long int word = __sigword (sig);
+  set->__val[word] &= ~mask;
+}
 
 #endif /* bits/sigsetops.h */