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Remove undefined behavior in OS X dumper.

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Found by Address Sanitizer.

* src/unexmacosx.c (unexec_write): Use Mach virtual memory API to
avoid undefined behavior when reading arbitrary memory.
This commit is contained in:
Philipp Stephani 2016-03-31 23:10:40 +02:00 • committed by John Wiegley
parent 97211f3630
commit b57076929f
1 changed files with 20 additions and 1 deletions
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21
src/unexmacosx.c
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@ -103,9 +103,11 @@ along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. */
#include <stdio.h>
#include <fcntl.h>
#include <stdarg.h>
#include <stdint.h>
#include <sys/types.h>
#include <unistd.h>
#include <mach/mach.h>
#include <mach/vm_map.h>
#include <mach-o/loader.h>
#include <mach-o/reloc.h>
#ifdef HAVE_MALLOC_MALLOC_H
@ -217,10 +219,27 @@ unexec_read (void *dest, size_t n)
static int
unexec_write (off_t dest, const void *src, size_t count)
{
task_t task = mach_task_self();
if (task == MACH_PORT_NULL || task == MACH_PORT_DEAD)
return false;
if (lseek (outfd, dest, SEEK_SET) != dest)
return 0;
return write (outfd, src, count) == count;
/* We use the Mach virtual memory API to read our process memory
because using src directly would be undefined behavior and fails
under Address Sanitizer. */
bool success = false;
vm_offset_t data;
mach_msg_type_number_t data_count;
if (vm_read (task, (uintptr_t) src, count, &data, &data_count)
== KERN_SUCCESS)
{
success =
write (outfd, (const void *) (uintptr_t) data, data_count) == count;
vm_deallocate (task, data, data_count);
}
return success;
}
/* Write COUNT bytes of zeros to outfd starting at offset DEST.