Improve buffer-overflow checking.

* fileio.c (Finsert_file_contents):
* insdel.c (insert_from_buffer_1, replace_range, replace_range_2):
Remove the old (too-loose) buffer overflow checks.
They weren't needed, since make_gap checks for buffer overflow.
* insdel.c (make_gap_larger): Catch buffer overflows that were missed.
The old code merely checked for Emacs fixnum overflow, and relied
on undefined (wraparound) behavior.  The new code avoids undefined
behavior, and also checks for ptrdiff_t and/or size_t overflow.

1 files changed, 10 insertions, 0 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 011f5beefe0..5f18c8d0062 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,5 +1,15 @@
 2011-06-16  Paul Eggert  <eggert@cs.ucla.edu>
 
+        Improve buffer-overflow checking.
+        * fileio.c (Finsert_file_contents):
+        * insdel.c (insert_from_buffer_1, replace_range, replace_range_2):
+        Remove the old (too-loose) buffer overflow checks.
+        They weren't needed, since make_gap checks for buffer overflow.
+        * insdel.c (make_gap_larger): Catch buffer overflows that were missed.
+        The old code merely checked for Emacs fixnum overflow, and relied
+        on undefined (wraparound) behavior.  The new code avoids undefined
+        behavior, and also checks for ptrdiff_t and/or size_t overflow.
+
         * editfns.c (Finsert_char): Don't dump core with very negative counts.
         Tune.  Don't use wider integers than needed.  Don't use alloca.
         Use a bigger 'string' buffer.  Rewrite to avoid 'n > 0' test.