[2.24 COMMITTED 1/5] [BZ #22637] Fix stack guard size accounting

[2.24 COMMITTED 1/5] [BZ #22637] Fix stack guard size accounting

[Aurelien Jarno]

From: Szabolcs Nagy <szabolcs.nagy@arm.com>

Previously if user requested S stack and G guard when creating a
thread, the total mapping was S and the actual available stack was
S - G - static_tls, which is not what the user requested.

This patch fixes the guard size accounting by pretending the user
requested S+G stack.  This way all later logic works out except
when reporting the user requested stack size (pthread_getattr_np)
or when computing the minimal stack size (__pthread_get_minstack).

Normally this will increase thread stack allocations by one page.
TLS accounting is not affected, that will require a separate fix.

	[BZ #22637]
	* nptl/descr.h (stackblock, stackblock_size): Update comments.
	* nptl/allocatestack.c (allocate_stack): Add guardsize to stacksize.
	* nptl/nptl-init.c (__pthread_get_minstack): Remove guardsize from
	stacksize.
	* nptl/pthread_getattr_np.c (pthread_getattr_np): Likewise.

(cherry picked from commit 630f4cc3aa019ede55976ea561f1a7af2f068639)
---
 ChangeLog                 | 9 +++++++++
 NEWS                      | 1 +
 nptl/allocatestack.c      | 4 ++++
 nptl/descr.h              | 4 ++--
 nptl/nptl-init.c          | 5 +----
 nptl/pthread_getattr_np.c | 7 +++++--
 6 files changed, 22 insertions(+), 8 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 988615f03b..7f37d678be 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2018-01-08  Szabolcs Nagy  <szabolcs.nagy@arm.com>
+
+	[BZ #22637]
+	* nptl/descr.h (stackblock, stackblock_size): Update comments.
+	* nptl/allocatestack.c (allocate_stack): Add guardsize to stacksize.
+	* nptl/nptl-init.c (__pthread_get_minstack): Remove guardsize from
+	stacksize.
+	* nptl/pthread_getattr_np.c (pthread_getattr_np): Likewise.
+
 2018-05-23  Andreas Schwab  <schwab@suse.de>
 
 	[BZ #23196]
diff --git a/NEWS b/NEWS
index 13ac8dd911..f2e9b3bf9f 100644
--- a/NEWS
+++ b/NEWS
@@ -71,6 +71,7 @@ The following bugs are resolved with this release:
   [21609] x86-64: Align the stack in __tls_get_addr
   [21624] Unsafe alloca allows local attackers to alias stack and heap (CVE-2017-1000366)
   [21654] nss: Fix invalid cast in group merging
+  [22637] nptl: Fix stack guard size accounting
   [22644] string: memmove-sse2-unaligned on 32bit x86 produces garbage when
     crossing 2GB threshold (CVE-2017-18269)
   [22715] x86-64: Properly align La_x86_64_retval to VEC_SIZE
diff --git a/nptl/allocatestack.c b/nptl/allocatestack.c
index 7365ca606b..9aba97fe7c 100644
--- a/nptl/allocatestack.c
+++ b/nptl/allocatestack.c
@@ -484,6 +484,10 @@ allocate_stack (const struct pthread_attr *attr, struct pthread **pdp,
       /* Make sure the size of the stack is enough for the guard and
 	 eventually the thread descriptor.  */
       guardsize = (attr->guardsize + pagesize_m1) & ~pagesize_m1;
+      if (guardsize < attr->guardsize || size + guardsize < guardsize)
+	/* Arithmetic overflow.  */
+	return EINVAL;
+      size += guardsize;
       if (__builtin_expect (size < ((guardsize + __static_tls_size
 				     + MINIMAL_REST_STACK + pagesize_m1)
 				    & ~pagesize_m1),
diff --git a/nptl/descr.h b/nptl/descr.h
index bc92abf010..7e62c3cb23 100644
--- a/nptl/descr.h
+++ b/nptl/descr.h
@@ -363,9 +363,9 @@ struct pthread
   /* Machine-specific unwind info.  */
   struct _Unwind_Exception exc;
 
-  /* If nonzero pointer to area allocated for the stack and its
-     size.  */
+  /* If nonzero, pointer to the area allocated for the stack and guard. */
   void *stackblock;
+  /* Size of the stackblock area including the guard.  */
   size_t stackblock_size;
   /* Size of the included guard area.  */
   size_t guardsize;
diff --git a/nptl/nptl-init.c b/nptl/nptl-init.c
index 48fab50c4e..4dabb64722 100644
--- a/nptl/nptl-init.c
+++ b/nptl/nptl-init.c
@@ -493,8 +493,5 @@ strong_alias (__pthread_initialize_minimal_internal,
 size_t
 __pthread_get_minstack (const pthread_attr_t *attr)
 {
-  struct pthread_attr *iattr = (struct pthread_attr *) attr;
-
-  return (GLRO(dl_pagesize) + __static_tls_size + PTHREAD_STACK_MIN
-	  + iattr->guardsize);
+  return GLRO(dl_pagesize) + __static_tls_size + PTHREAD_STACK_MIN;
 }
diff --git a/nptl/pthread_getattr_np.c b/nptl/pthread_getattr_np.c
index 32d7484bf8..c2dfa13fa9 100644
--- a/nptl/pthread_getattr_np.c
+++ b/nptl/pthread_getattr_np.c
@@ -57,9 +57,12 @@ pthread_getattr_np (pthread_t thread_id, pthread_attr_t *attr)
   /* The sizes are subject to alignment.  */
   if (__glibc_likely (thread->stackblock != NULL))
     {
-      iattr->stacksize = thread->stackblock_size;
+      /* The stack size reported to the user should not include the
+	 guard size.  */
+      iattr->stacksize = thread->stackblock_size - thread->guardsize;
 #if _STACK_GROWS_DOWN
-      iattr->stackaddr = (char *) thread->stackblock + iattr->stacksize;
+      iattr->stackaddr = (char *) thread->stackblock
+			 + thread->stackblock_size;
 #else
       iattr->stackaddr = (char *) thread->stackblock;
 #endif
-- 
2.19.2

[2.24 COMMITTED 3/5] nptl: Add tst-minstack-cancel, tst-minstack-exit [BZ #22636]

[Aurelien Jarno]

From: Florian Weimer <fweimer@redhat.com>

I verified that without the guard accounting change in commit
630f4cc3aa019ede55976ea561f1a7af2f068639 (Fix stack guard size
accounting) and RTLD_NOW for libgcc_s introduced by commit
f993b8754080ac7572b692870e926d8b493db16c (nptl: Open libgcc.so with
RTLD_NOW during pthread_cancel), the tst-minstack-cancel test fails on
an AVX-512F machine.  tst-minstack-exit still passes, and either of
the mentioned commit by itself frees sufficient stack space to make
tst-minstack-cancel pass, too.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
(cherry picked from commit d8b778907e5270fdeb70459842ffbc20bd2ca5e1)
---
 ChangeLog                  |  6 +++++
 nptl/Makefile              |  4 +++-
 nptl/tst-minstack-cancel.c | 48 ++++++++++++++++++++++++++++++++++++++
 nptl/tst-minstack-exit.c   | 46 ++++++++++++++++++++++++++++++++++++
 4 files changed, 103 insertions(+), 1 deletion(-)
 create mode 100644 nptl/tst-minstack-cancel.c
 create mode 100644 nptl/tst-minstack-exit.c

diff --git a/ChangeLog b/ChangeLog
index 48292d6bf0..1062e4fa59 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2018-01-11  Florian Weimer  <fweimer@redhat.com>
+
+	[BZ #22636]
+	* nptl/Makefile (tests): Add tst-minstack-cancel, tst-minstack-exit.
+	* nptl/tst-minstack-cancel.c, nptl/tst-minstack-exit.c: New files.
+
 2018-01-10  Florian Weimer  <fweimer@redhat.com>
 
 	[BZ #22636]
diff --git a/nptl/Makefile b/nptl/Makefile
index fa925819ca..1aa52afd71 100644
--- a/nptl/Makefile
+++ b/nptl/Makefile
@@ -290,7 +290,9 @@ tests = tst-typesizes \
 	tst-initializers1 $(addprefix tst-initializers1-,\
 			    c89 gnu89 c99 gnu99 c11 gnu11) \
 	tst-bad-schedattr \
-	tst-thread_local1 tst-mutex-errorcheck tst-robust10
+	tst-thread_local1 tst-mutex-errorcheck tst-robust10 \
+	tst-minstack-cancel tst-minstack-exit
+
 xtests = tst-setuid1 tst-setuid1-static tst-setuid2 \
 	tst-mutexpp1 tst-mutexpp6 tst-mutexpp10
 test-srcs = tst-oddstacklimit
diff --git a/nptl/tst-minstack-cancel.c b/nptl/tst-minstack-cancel.c
new file mode 100644
index 0000000000..a306320e88
--- /dev/null
+++ b/nptl/tst-minstack-cancel.c
@@ -0,0 +1,48 @@
+/* Test cancellation with a minimal stack size.
+   Copyright (C) 2018 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
+   <http://www.gnu.org/licenses/>.  */
+
+/* Note: This test is similar to tst-minstack-exit, but is separate to
+   avoid spurious test passes due to warm-up effects.  */
+
+#include <limits.h>
+#include <unistd.h>
+#include <support/check.h>
+#include <support/xthread.h>
+
+static void *
+threadfunc (void *closure)
+{
+  while (1)
+    pause ();
+  return NULL;
+}
+
+static int
+do_test (void)
+{
+  pthread_attr_t attr;
+  xpthread_attr_init (&attr);
+  xpthread_attr_setstacksize (&attr, PTHREAD_STACK_MIN);
+  pthread_t thr = xpthread_create (&attr, threadfunc, NULL);
+  xpthread_cancel (thr);
+  TEST_VERIFY (xpthread_join (thr) == PTHREAD_CANCELED);
+  xpthread_attr_destroy (&attr);
+  return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/nptl/tst-minstack-exit.c b/nptl/tst-minstack-exit.c
new file mode 100644
index 0000000000..9c7e9a4dfe
--- /dev/null
+++ b/nptl/tst-minstack-exit.c
@@ -0,0 +1,46 @@
+/* Test that pthread_exit works with the minimum stack size.
+   Copyright (C) 2018 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
+   <http://www.gnu.org/licenses/>.  */
+
+/* Note: This test is similar to tst-minstack-cancel, but is separate
+   to avoid spurious test passes due to warm-up effects.  */
+
+#include <limits.h>
+#include <unistd.h>
+#include <support/check.h>
+#include <support/xthread.h>
+
+static void *
+threadfunc (void *closure)
+{
+  pthread_exit (threadfunc);
+  return NULL;
+}
+
+static int
+do_test (void)
+{
+  pthread_attr_t attr;
+  xpthread_attr_init (&attr);
+  xpthread_attr_setstacksize (&attr, PTHREAD_STACK_MIN);
+  pthread_t thr = xpthread_create (&attr, threadfunc, NULL);
+  TEST_VERIFY (xpthread_join (thr) == threadfunc);
+  xpthread_attr_destroy (&attr);
+  return 0;
+}
+
+#include <support/test-driver.c>
-- 
2.19.2

[2.24 COMMITTED 5/5] csu: Update __libgcc_s_init comment

[Aurelien Jarno]

From: Florian Weimer <fweimer@redhat.com>

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
(cherry picked from commit 08c6e95234c60a5c2f37532d1111acf084f39345)
---
 ChangeLog                   | 5 +++++
 sysdeps/gnu/unwind-resume.c | 8 ++++++--
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 4d6686a9f5..82767ac063 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2018-01-11  Florian Weimer  <fweimer@redhat.com>
+
+	* sysdeps/gnu/unwind-resume.c (__libgcc_s_init): Update comment
+	and error message.
+
 2018-01-16  Florian Weimer  <fweimer@redhat.com>
 
 	* nptl/Makefile (CFLAGS-tst-minstack-throw.o): Compile in C++11
diff --git a/sysdeps/gnu/unwind-resume.c b/sysdeps/gnu/unwind-resume.c
index 5d25e73dd1..e81b65692a 100644
--- a/sysdeps/gnu/unwind-resume.c
+++ b/sysdeps/gnu/unwind-resume.c
@@ -35,13 +35,17 @@ __libgcc_s_init (void)
   void *resume, *personality;
   void *handle;
 
-  handle = __libc_dlopen (LIBGCC_S_SO);
+  /* Use RTLD_NOW here for consistency with pthread_cancel_init.
+     RTLD_NOW will rarely make a difference here because unwinding is
+     already in progress, so libgcc_s.so has already been loaded if
+     its unwinder is used.  */
+  handle = __libc_dlopen_mode (LIBGCC_S_SO, RTLD_NOW | __RTLD_DLOPEN);
 
   if (handle == NULL
       || (resume = __libc_dlsym (handle, "_Unwind_Resume")) == NULL
       || (personality = __libc_dlsym (handle, "__gcc_personality_v0")) == NULL)
     __libc_fatal (LIBGCC_S_SO
-                  " must be installed for pthread_cancel to work\n");
+                  " must be installed for unwinding to work\n");
 
 #ifdef PTR_MANGLE
   PTR_MANGLE (resume);
-- 
2.19.2

[2.24 COMMITTED 4/5] nptl/tst-minstack-throw: Compile in C++11 mode with GNU extensions

[Aurelien Jarno]

From: Florian Weimer <fweimer@redhat.com>

(cherry picked from commit b725132d2b0aeddf970b1ce3e5a24f8637a7b4c2)
---
 ChangeLog | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/ChangeLog b/ChangeLog
index 1062e4fa59..4d6686a9f5 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2018-01-16  Florian Weimer  <fweimer@redhat.com>
+
+	* nptl/Makefile (CFLAGS-tst-minstack-throw.o): Compile in C++11
+	mode with GNU extensions.
+
 2018-01-11  Florian Weimer  <fweimer@redhat.com>
 
 	[BZ #22636]
-- 
2.19.2

[2.24 COMMITTED 2/5] nptl: Open libgcc.so with RTLD_NOW during pthread_cancel [BZ #22636]

[Aurelien Jarno]

From: Florian Weimer <fweimer@redhat.com>

Disabling lazy binding reduces stack usage during unwinding.

Note that RTLD_NOW only makes a difference if libgcc.so has not
already been loaded, so this is only a partial fix.

Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
(cherry picked from commit f993b8754080ac7572b692870e926d8b493db16c)
---
 ChangeLog                          | 6 ++++++
 NEWS                               | 1 +
 sysdeps/nptl/unwind-forcedunwind.c | 2 +-
 3 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/ChangeLog b/ChangeLog
index 7f37d678be..48292d6bf0 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2018-01-10  Florian Weimer  <fweimer@redhat.com>
+
+	[BZ #22636]
+	* sysdeps/nptl/unwind-forcedunwind.c (pthread_cancel_init): Open
+	libgcc.so with RTLD_NOW, to avoid lazy binding during unwind.
+
 2018-01-08  Szabolcs Nagy  <szabolcs.nagy@arm.com>
 
 	[BZ #22637]
diff --git a/NEWS b/NEWS
index f2e9b3bf9f..9a11b86b11 100644
--- a/NEWS
+++ b/NEWS
@@ -71,6 +71,7 @@ The following bugs are resolved with this release:
   [21609] x86-64: Align the stack in __tls_get_addr
   [21624] Unsafe alloca allows local attackers to alias stack and heap (CVE-2017-1000366)
   [21654] nss: Fix invalid cast in group merging
+  [22636] PTHREAD_STACK_MIN is too small on x86-64
   [22637] nptl: Fix stack guard size accounting
   [22644] string: memmove-sse2-unaligned on 32bit x86 produces garbage when
     crossing 2GB threshold (CVE-2017-18269)
diff --git a/sysdeps/nptl/unwind-forcedunwind.c b/sysdeps/nptl/unwind-forcedunwind.c
index ca757c48ce..24a1c5b30d 100644
--- a/sysdeps/nptl/unwind-forcedunwind.c
+++ b/sysdeps/nptl/unwind-forcedunwind.c
@@ -49,7 +49,7 @@ pthread_cancel_init (void)
       return;
     }
 
-  handle = __libc_dlopen (LIBGCC_S_SO);
+  handle = __libc_dlopen_mode (LIBGCC_S_SO, RTLD_NOW | __RTLD_DLOPEN);
 
   if (handle == NULL
       || (resume = __libc_dlsym (handle, "_Unwind_Resume")) == NULL
-- 
2.19.2