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-rw-r--r--src/ChangeLog26
-rw-r--r--src/buffer.h6
-rw-r--r--src/editfns.c27
-rw-r--r--src/fileio.c13
-rw-r--r--src/insdel.c44
-rw-r--r--src/lisp.h1
6 files changed, 60 insertions, 57 deletions
diff --git a/src/ChangeLog b/src/ChangeLog
index 59fb2d89b24..5f18c8d0062 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,29 @@
+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.
+
+ * insdel.c (replace_range): Fix buf overflow when insbytes < outgoing.
+
+ * insdel.c, lisp.h (buffer_overflow): New function.
+ (insert_from_buffer_1, replace_range, replace_range_2):
+ * insdel.c (make_gap_larger):
+ * editfns.c (Finsert_char):
+ * fileio.c (Finsert_file_contents): Use it, to normalize wording.
+
+ * buffer.h (BUF_BYTES_MAX): Cast to ptrdiff_t so that it's signed.
+
2011-06-15 Paul Eggert <eggert@cs.ucla.edu>
Integer overflow and signedness fixes (Bug#8873).
diff --git a/src/buffer.h b/src/buffer.h
index dc1d62beb00..a13351b5ea6 100644
--- a/src/buffer.h
+++ b/src/buffer.h
@@ -309,8 +309,10 @@ while (0)
/* Maximum number of bytes in a buffer.
A buffer cannot contain more bytes than a 1-origin fixnum can represent,
- nor can it be so large that C pointer arithmetic stops working. */
-#define BUF_BYTES_MAX min (MOST_POSITIVE_FIXNUM - 1, min (SIZE_MAX, PTRDIFF_MAX))
+ nor can it be so large that C pointer arithmetic stops working.
+ The ptrdiff_t cast ensures that this is signed, not unsigned. */
+#define BUF_BYTES_MAX \
+ (ptrdiff_t) min (MOST_POSITIVE_FIXNUM - 1, min (SIZE_MAX, PTRDIFF_MAX))
/* Return the address of byte position N in current buffer. */
diff --git a/src/editfns.c b/src/editfns.c
index 9678d4da6a2..2d736bbc7e2 100644
--- a/src/editfns.c
+++ b/src/editfns.c
@@ -2328,12 +2328,11 @@ The optional third arg INHERIT, if non-nil, says to inherit text properties
from adjoining text, if those properties are sticky. */)
(Lisp_Object character, Lisp_Object count, Lisp_Object inherit)
{
- register char *string;
- register EMACS_INT stringlen;
- register int i;
+ int i, stringlen;
register EMACS_INT n;
int c, len;
unsigned char str[MAX_MULTIBYTE_LENGTH];
+ char string[4000];
CHECK_CHARACTER (character);
CHECK_NUMBER (count);
@@ -2343,16 +2342,15 @@ from adjoining text, if those properties are sticky. */)
len = CHAR_STRING (c, str);
else
str[0] = c, len = 1;
+ if (XINT (count) <= 0)
+ return Qnil;
if (BUF_BYTES_MAX / len < XINT (count))
- error ("Maximum buffer size would be exceeded");
+ buffer_overflow ();
n = XINT (count) * len;
- if (n <= 0)
- return Qnil;
- stringlen = min (n, 256 * len);
- string = (char *) alloca (stringlen);
+ stringlen = min (n, sizeof string - sizeof string % len);
for (i = 0; i < stringlen; i++)
string[i] = str[i % len];
- while (n >= stringlen)
+ while (n > stringlen)
{
QUIT;
if (!NILP (inherit))
@@ -2361,13 +2359,10 @@ from adjoining text, if those properties are sticky. */)
insert (string, stringlen);
n -= stringlen;
}
- if (n > 0)
- {
- if (!NILP (inherit))
- insert_and_inherit (string, n);
- else
- insert (string, n);
- }
+ if (!NILP (inherit))
+ insert_and_inherit (string, n);
+ else
+ insert (string, n);
return Qnil;
}
diff --git a/src/fileio.c b/src/fileio.c
index fd5277cbd59..dd34872c263 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -3264,7 +3264,7 @@ variable `last-coding-system-used' to the coding system actually used. */)
platform that allows file sizes greater than the maximum off_t value. */
if (! not_regular
&& ! (0 <= st.st_size && st.st_size <= BUF_BYTES_MAX))
- error ("Maximum buffer size exceeded");
+ buffer_overflow ();
/* Prevent redisplay optimizations. */
current_buffer->clip_changed = 1;
@@ -3800,16 +3800,7 @@ variable `last-coding-system-used' to the coding system actually used. */)
}
if (! not_regular)
- {
- register Lisp_Object temp;
-
- total = XINT (end) - XINT (beg);
-
- /* Make sure point-max won't overflow after this insertion. */
- XSETINT (temp, total);
- if (total != XINT (temp))
- error ("Maximum buffer size exceeded");
- }
+ total = XINT (end) - XINT (beg);
else
/* For a special file, all we can do is guess. */
total = READ_BUF_SIZE;
diff --git a/src/insdel.c b/src/insdel.c
index c0cccc65d6a..bc95e3ad9e8 100644
--- a/src/insdel.c
+++ b/src/insdel.c
@@ -391,6 +391,12 @@ adjust_markers_for_replace (EMACS_INT from, EMACS_INT from_byte,
}
+void
+buffer_overflow (void)
+{
+ error ("Maximum buffer size exceeded");
+}
+
/* Make the gap NBYTES_ADDED bytes longer. */
static void
@@ -400,16 +406,16 @@ make_gap_larger (EMACS_INT nbytes_added)
EMACS_INT real_gap_loc;
EMACS_INT real_gap_loc_byte;
EMACS_INT old_gap_size;
+ EMACS_INT current_size = Z_BYTE - BEG_BYTE + GAP_SIZE;
+ enum { enough_for_a_while = 2000 };
- /* If we have to get more space, get enough to last a while. */
- nbytes_added += 2000;
+ if (BUF_BYTES_MAX - current_size < nbytes_added)
+ buffer_overflow ();
- { EMACS_INT total_size = Z_BYTE - BEG_BYTE + GAP_SIZE + nbytes_added;
- if (total_size < 0
- /* Don't allow a buffer size that won't fit in a Lisp integer. */
- || total_size != XINT (make_number (total_size)))
- error ("Buffer exceeds maximum size");
- }
+ /* If we have to get more space, get enough to last a while;
+ but do not exceed the maximum buffer size. */
+ nbytes_added = min (nbytes_added + enough_for_a_while,
+ BUF_BYTES_MAX - current_size);
enlarge_buffer_text (current_buffer, nbytes_added);
@@ -1063,7 +1069,6 @@ static void
insert_from_buffer_1 (struct buffer *buf,
EMACS_INT from, EMACS_INT nchars, int inherit)
{
- register Lisp_Object temp;
EMACS_INT chunk, chunk_expanded;
EMACS_INT from_byte = buf_charpos_to_bytepos (buf, from);
EMACS_INT to_byte = buf_charpos_to_bytepos (buf, from + nchars);
@@ -1102,11 +1107,6 @@ insert_from_buffer_1 (struct buffer *buf,
outgoing_nbytes = outgoing_before_gap + outgoing_after_gap;
}
- /* Make sure point-max won't overflow after this insertion. */
- XSETINT (temp, outgoing_nbytes + Z);
- if (outgoing_nbytes + Z != XINT (temp))
- error ("Maximum buffer size exceeded");
-
/* Do this before moving and increasing the gap,
because the before-change hooks might move the gap
or make it smaller. */
@@ -1303,7 +1303,6 @@ replace_range (EMACS_INT from, EMACS_INT to, Lisp_Object new,
EMACS_INT insbytes = SBYTES (new);
EMACS_INT from_byte, to_byte;
EMACS_INT nbytes_del, nchars_del;
- register Lisp_Object temp;
struct gcpro gcpro1;
INTERVAL intervals;
EMACS_INT outgoing_insbytes = insbytes;
@@ -1347,11 +1346,6 @@ replace_range (EMACS_INT from, EMACS_INT to, Lisp_Object new,
outgoing_insbytes
= count_size_as_multibyte (SDATA (new), insbytes);
- /* Make sure point-max won't overflow after this insertion. */
- XSETINT (temp, Z_BYTE - nbytes_del + insbytes);
- if (Z_BYTE - nbytes_del + insbytes != XINT (temp))
- error ("Maximum buffer size exceeded");
-
GCPRO1 (new);
/* Make sure the gap is somewhere in or next to what we are deleting. */
@@ -1383,8 +1377,8 @@ replace_range (EMACS_INT from, EMACS_INT to, Lisp_Object new,
if (Z - GPT < END_UNCHANGED)
END_UNCHANGED = Z - GPT;
- if (GAP_SIZE < insbytes)
- make_gap (insbytes - GAP_SIZE);
+ if (GAP_SIZE < outgoing_insbytes)
+ make_gap (outgoing_insbytes - GAP_SIZE);
/* Copy the string text into the buffer, perhaps converting
between single-byte and multibyte. */
@@ -1482,7 +1476,6 @@ replace_range_2 (EMACS_INT from, EMACS_INT from_byte,
int markers)
{
EMACS_INT nbytes_del, nchars_del;
- Lisp_Object temp;
CHECK_MARKERS ();
@@ -1492,11 +1485,6 @@ replace_range_2 (EMACS_INT from, EMACS_INT from_byte,
if (nbytes_del <= 0 && insbytes == 0)
return;
- /* Make sure point-max won't overflow after this insertion. */
- XSETINT (temp, Z_BYTE - nbytes_del + insbytes);
- if (Z_BYTE - nbytes_del + insbytes != XINT (temp))
- error ("Maximum buffer size exceeded");
-
/* Make sure the gap is somewhere in or next to what we are deleting. */
if (from > GPT)
gap_right (from, from_byte);
diff --git a/src/lisp.h b/src/lisp.h
index 83534e55433..75827deda1a 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -2635,6 +2635,7 @@ extern void init_image (void);
extern Lisp_Object Qinhibit_modification_hooks;
extern void move_gap (EMACS_INT);
extern void move_gap_both (EMACS_INT, EMACS_INT);
+extern void buffer_overflow (void) NO_RETURN;
extern void make_gap (EMACS_INT);
extern EMACS_INT copy_text (const unsigned char *, unsigned char *,
EMACS_INT, int, int);
generated by cgit v1.2.3 (git 2.39.1) at 2025-06-23 14:17:43 +0000