Refactor Linux raise implementation (BZ#15368)

This patch changes both the nptl and libc Linux raise implementation
to avoid the issues described in BZ#15368.  The strategy used is
summarized in bug report first comment:

 1. Block all signals (including internal NPTL ones);
 2. Get pid and tid directly from syscall (not relying on cached
    values);
 3. Call tgkill;
 4. Restore old signal mask.

Tested on x86_64 and i686.

	[BZ #15368]
	* sysdeps/unix/sysv/linux/nptl-signals.h
	(__nptl_clear_internal_signals): New function.
	(__libc_signal_block_all): Likewise.
	(__libc_signal_block_app): Likewise.
	(__libc_signal_restore_set): Likewise.
	* sysdeps/unix/sysv/linux/pt-raise.c (raise): Use Linux raise.c
	implementation.
	* sysdeps/unix/sysv/linux/raise.c (raise): Reimplement to not use
	the cached pid/tid value in pthread structure.

diff --git a/ChangeLog b/ChangeLog
index ed5daf1..4bc8a61 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,16 @@
+2016-07-13  Adhemerval Zanella  <adhemerval.zanella@linaro.org>
+
+       [BZ #15368]
+       * sysdeps/unix/sysv/linux/nptl-signals.h
+       (__nptl_clear_internal_signals): New function.
+       (__libc_signal_block_all): Likewise.
+       (__libc_signal_block_app): Likewise.
+       (__libc_signal_restore_set): Likewise.
+       * sysdeps/unix/sysv/linux/pt-raise.c (raise): Use Linux raise.c
+       implementation.
+       * sysdeps/unix/sysv/linux/raise.c (raise): Reimplement to not use
+       the cached pid/tid value in pthread structure.
+
 2016-07-13  H.J. Lu  <hongjiu.lu@intel.com>
 
        [BZ #20347]

diff --git a/sysdeps/unix/sysv/linux/nptl-signals.h b/sysdeps/unix/sysv/linux/nptl-signals.h
index 01f34c2..2710159 100644 (file)
--- a/sysdeps/unix/sysv/linux/nptl-signals.h
+++ b/sysdeps/unix/sysv/linux/nptl-signals.h
@@ -39,5 +39,46 @@ __nptl_is_internal_signal (int sig)
   return (sig == SIGCANCEL) || (sig == SIGTIMER) || (sig == SIGSETXID);
 }
 
+/* Remove internal glibc signal from the mask.  */
+static inline void
+__nptl_clear_internal_signals (sigset_t *set)
+{
+  __sigdelset (set, SIGCANCEL);
+  __sigdelset (set, SIGTIMER);
+  __sigdelset (set, SIGSETXID);
+}
+
+#define SIGALL_SET \
+  ((__sigset_t) { .__val = {[0 ...  _SIGSET_NWORDS-1 ] =  -1 } })
+
+/* Block all signals, including internal glibc ones.  */
+static inline int
+__libc_signal_block_all (sigset_t *set)
+{
+  INTERNAL_SYSCALL_DECL (err);
+  return INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_BLOCK, &SIGALL_SET,
+                          set, _NSIG / 8);
+}
+
+/* Block all application signals (excluding internal glibc ones).  */
+static inline int
+__libc_signal_block_app (sigset_t *set)
+{
+  sigset_t allset = SIGALL_SET;
+  __nptl_clear_internal_signals (&allset);
+  INTERNAL_SYSCALL_DECL (err);
+  return INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_BLOCK, &allset, set,
+                          _NSIG / 8);
+}
+
+/* Restore current process signal mask.  */
+static inline int
+__libc_signal_restore_set (const sigset_t *set)
+{
+  INTERNAL_SYSCALL_DECL (err);
+  return INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_SETMASK, set, NULL,
+                          _NSIG / 8);
+}
+
 /* Used to communicate with signal handler.  */
 extern struct xid_command *__xidcmd attribute_hidden;

diff --git a/sysdeps/unix/sysv/linux/pt-raise.c b/sysdeps/unix/sysv/linux/pt-raise.c
index 715bbe9..5f6dea1 100644 (file)
--- a/sysdeps/unix/sysv/linux/pt-raise.c
+++ b/sysdeps/unix/sysv/linux/pt-raise.c
@@ -1,4 +1,5 @@
-/* Copyright (C) 2002-2016 Free Software Foundation, Inc.
+/* ISO C raise function for libpthread.
+   Copyright (C) 2002-2016 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
    Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
 
@@ -16,22 +17,4 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-#include <errno.h>
-#include <signal.h>
-#include <sysdep.h>
-#include <tls.h>
-
-
-int
-raise (int sig)
-{
-  /* raise is an async-safe function.  It could be called while the
-     fork function temporarily invalidated the PID field.  Adjust for
-     that.  */
-  pid_t pid = THREAD_GETMEM (THREAD_SELF, pid);
-  if (__glibc_unlikely (pid < 0))
-    pid = -pid;
-
-  return INLINE_SYSCALL (tgkill, 3, pid, THREAD_GETMEM (THREAD_SELF, tid),
-                        sig);
-}
+#include <sysdeps/unix/sysv/linux/raise.c>

diff --git a/sysdeps/unix/sysv/linux/raise.c b/sysdeps/unix/sysv/linux/raise.c
index 3795e6e..470033e 100644 (file)
--- a/sysdeps/unix/sysv/linux/raise.c
+++ b/sysdeps/unix/sysv/linux/raise.c
@@ -16,42 +16,45 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-#include <errno.h>
-#include <limits.h>
 #include <signal.h>
 #include <sysdep.h>
-#include <nptl/pthreadP.h>
-
+#include <errno.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <nptl-signals.h>
 
 int
 raise (int sig)
 {
-  struct pthread *pd = THREAD_SELF;
-  pid_t pid = THREAD_GETMEM (pd, pid);
-  pid_t selftid = THREAD_GETMEM (pd, tid);
-  if (selftid == 0)
-    {
-      /* This system call is not supposed to fail.  */
-#ifdef INTERNAL_SYSCALL
-      INTERNAL_SYSCALL_DECL (err);
-      selftid = INTERNAL_SYSCALL (gettid, err, 0);
-#else
-      selftid = INLINE_SYSCALL (gettid, 0);
-#endif
-      THREAD_SETMEM (pd, tid, selftid);
-
-      /* We do not set the PID field in the TID here since we might be
-        called from a signal handler while the thread executes fork.  */
-      pid = selftid;
-    }
-  else
-    /* raise is an async-safe function.  It could be called while the
-       fork/vfork function temporarily invalidated the PID field.  Adjust for
-       that.  */
-    if (__glibc_unlikely (pid <= 0))
-      pid = (pid & INT_MAX) == 0 ? selftid : -pid;
-
-  return INLINE_SYSCALL (tgkill, 3, pid, selftid, sig);
+  /* raise is an async-safe function so it could be called while the
+     fork/vfork function temporarily invalidated the PID field.  To avoid
+     relying on cached value we block all user-defined signal handler
+     (which might call fork/vfork) and issue the getpid and gettid
+     syscalls directly.  */
+
+
+  /* rt_sigprocmask may fail if:
+
+     1. sigsetsize != sizeof (sigset_t) (EINVAL)
+     2. a failure in copy from/to user space (EFAULT)
+     3. an invalid 'how' operation (EINVAL)
+
+     The first case is already handle in glibc syscall call by using the arch
+     defined _NSIG.  Second case is handled by using a stack allocated mask.
+     The last one should be handled by the block/unblock functions.  */
+
+  sigset_t set;
+  __libc_signal_block_app (&set);
+
+  INTERNAL_SYSCALL_DECL (err);
+  pid_t pid = INTERNAL_SYSCALL (getpid, err, 0);
+  pid_t tid = INTERNAL_SYSCALL (gettid, err, 0);
+
+  int ret = INLINE_SYSCALL (tgkill, 3, pid, tid, sig);
+
+  __libc_signal_restore_set (&set);
+
+  return ret;
 }
 libc_hidden_def (raise)
 weak_alias (raise, gsignal)