[PATCH][BZ #15618] Avoid access beyond memory bounds in pthread_attr_getaffinity_np

[Siddhesh Poyarekar <siddhesh at redhat dot com>]

Hi,

pthread_attr_getaffinity_np may write beyond bounds of the input
cpuset buffer if the size of the input buffer is smaller than the
buffer present in the input pthread attributes.  Fix is to copy to the
extent of the minimum of the source and the destination.

I've added a test case to verify the fix and have verified that the
patch fixes the test case.

Siddhesh

2013-06-13  Siddhesh Poyarekar  <siddhesh@redhat.com>
	    Carlos O'Donell  <carlos@redhat.com>

	[BZ #15618]
	* tst-pthread-attr-affinity: New test case.
	* Makefile (tests): Add it.
	* sysdeps/unix/sysv/linux/pthread_attr_getaffinity.c
	(__pthread_attr_getaffinity_new): Copy minimum of source and
	destination sizes to avoid a buffer overrun.


diff --git a/nptl/Makefile b/nptl/Makefile
index f1fbf25..cd601e5 100644
--- a/nptl/Makefile
+++ b/nptl/Makefile
@@ -253,6 +253,7 @@ tests = tst-typesizes \
 	tst-exit1 tst-exit2 tst-exit3 \
 	tst-stdio1 tst-stdio2 \
 	tst-stack1 tst-stack2 tst-stack3 tst-pthread-getattr \
+	tst-pthread-attr-affinity \
 	tst-unload \
 	tst-dlsym1 \
 	tst-sysconf \
diff --git a/nptl/sysdeps/unix/sysv/linux/pthread_attr_getaffinity.c b/nptl/sysdeps/unix/sysv/linux/pthread_attr_getaffinity.c
index 00bb29b..7cae348 100644
--- a/nptl/sysdeps/unix/sysv/linux/pthread_attr_getaffinity.c
+++ b/nptl/sysdeps/unix/sysv/linux/pthread_attr_getaffinity.c
@@ -42,7 +42,8 @@ __pthread_attr_getaffinity_new (const pthread_attr_t *attr, size_t cpusetsize,
 	if (((char *) iattr->cpuset)[cnt] != 0)
 	  return EINVAL;
 
-      void *p = mempcpy (cpuset, iattr->cpuset, iattr->cpusetsize);
+      void *p = mempcpy (cpuset, iattr->cpuset,
+			 MIN (iattr->cpusetsize, cpusetsize));
       if (cpusetsize > iattr->cpusetsize)
 	memset (p, '\0', cpusetsize - iattr->cpusetsize);
     }
diff --git a/nptl/tst-pthread-attr-affinity.c b/nptl/tst-pthread-attr-affinity.c
new file mode 100644
index 0000000..c8f6dbb
--- /dev/null
+++ b/nptl/tst-pthread-attr-affinity.c
@@ -0,0 +1,62 @@
+/* Make sure that pthread_attr_getaffinity_np does not crash when the input
+   cpuset size is smaller than that in the attribute structure.
+
+   Copyright (C) 2013 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/>.  */
+
+#include <pthread.h>
+#include <stdio.h>
+#include <sched.h>
+#include <errno.h>
+
+
+#define RETURN_IF_FAIL(f, ...) \
+  ({									      \
+    int ret = f (__VA_ARGS__);						      \
+    if (ret != 0)							      \
+      {									      \
+	printf ("%s:%d: %s returned %d (errno = %d)\n", __FILE__, __LINE__,   \
+		#f, ret, errno);					      \
+	return ret;							      \
+      }									      \
+  })
+
+static int
+do_test (void)
+{
+  for (int i = 0; i < 10; i++)
+    {
+      pthread_attr_t attr;
+      cpu_set_t *cpuset = CPU_ALLOC (512);
+      size_t cpusetsize = CPU_ALLOC_SIZE (512);
+      CPU_ZERO_S (cpusetsize, cpuset);
+
+      RETURN_IF_FAIL (pthread_attr_init, &attr);
+      RETURN_IF_FAIL (pthread_attr_setaffinity_np, &attr, cpusetsize, cpuset);
+      CPU_FREE (cpuset);
+
+      cpuset = CPU_ALLOC (1);
+      cpusetsize = CPU_ALLOC_SIZE (1);
+      RETURN_IF_FAIL (pthread_attr_getaffinity_np, &attr, cpusetsize, cpuset);
+      CPU_FREE (cpuset);
+    }
+  return 0;
+}
+
+
+#define TEST_FUNCTION do_test ()
+#include "../test-skeleton.c"