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[Emacs-diffs] emacs-25 b570769: Remove undefined behavior in OS X dumper
From: |
John Wiegley |
Subject: |
[Emacs-diffs] emacs-25 b570769: Remove undefined behavior in OS X dumper. |
Date: |
Sat, 09 Apr 2016 19:54:49 +0000 |
branch: emacs-25
commit b57076929f0e904864e1457d5789f2fe6652fc84
Author: Philipp Stephani <address@hidden>
Commit: John Wiegley <address@hidden>
Remove undefined behavior in OS X dumper.
Found by Address Sanitizer.
* src/unexmacosx.c (unexec_write): Use Mach virtual memory API to
avoid undefined behavior when reading arbitrary memory.
---
src/unexmacosx.c | 21 ++++++++++++++++++++-
1 files changed, 20 insertions(+), 1 deletions(-)
diff --git a/src/unexmacosx.c b/src/unexmacosx.c
index 827eda5..bdacc8b 100644
--- a/src/unexmacosx.c
+++ b/src/unexmacosx.c
@@ -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.
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