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Avoid integer overflows in the base64 functions. Fixes CVE-2008-4316

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2009-03-12  Matthias Clasen  <mclasen@redhat.com>

        * glib/gbase64.c: Avoid integer overflows in the base64
        functions. Fixes CVE-2008-4316


svn path=/trunk/; revision=7973
This commit is contained in:
Matthias Clasen 2009-03-12 13:30:55 +00:00 committed by Matthias Clasen
parent be600f638f
commit 2ad1af5b1e
2 changed files with 23 additions and 7 deletions
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5
ChangeLog
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@ -1,3 +1,8 @@
2009-03-12 Matthias Clasen <mclasen@redhat.com>
* glib/gbase64.c: Avoid integer overflows in the base64
functions. Fixes CVE-2008-4316
2009-03-11 Stef Walter <stef@memberwebs.com>
* glib/gchecksum.c: Document and guarantee hex digests will

25
glib/gbase64.c
View File

@ -54,8 +54,9 @@ static const char base64_alphabet[] =
*
* The output buffer must be large enough to fit all the data that will
* be written to it. Due to the way base64 encodes you will need
* at least: @len * 4 / 3 + 6 bytes. If you enable line-breaking you will
* need at least: @len * 4 / 3 + @len * 4 / (3 * 72) + 7 bytes.
* at least: (@len / 3 + 1) * 4 + 4 bytes (+ 4 may be needed in case of
* non-zero state). If you enable line-breaking you will need at least:
* ((@len / 3 + 1) * 4 + 4) / 72 + 1 bytes of extra space.
*
* @break_lines is typically used when putting base64-encoded data in emails.
* It breaks the lines at 72 columns instead of putting all of the text on
@ -233,8 +234,14 @@ g_base64_encode (const guchar *data,
g_return_val_if_fail (data != NULL, NULL);
g_return_val_if_fail (len > 0, NULL);
/* We can use a smaller limit here, since we know the saved state is 0 */
out = g_malloc (len * 4 / 3 + 4);
/* We can use a smaller limit here, since we know the saved state is 0,
+1 is needed for trailing \0, also check for unlikely integer overflow */
if (len >= ((G_MAXSIZE - 1) / 4 - 1) * 3)
g_error("%s: input too large for Base64 encoding (%"G_GSIZE_FORMAT" chars)",
G_STRLOC, len);
out = g_malloc ((len / 3 + 1) * 4 + 1);
outlen = g_base64_encode_step (data, len, FALSE, out, &state, &save);
outlen += g_base64_encode_close (FALSE, out + outlen, &state, &save);
out[outlen] = '\0';
@ -275,7 +282,8 @@ static const unsigned char mime_base64_rank[256] = {
*
* The output buffer must be large enough to fit all the data that will
* be written to it. Since base64 encodes 3 bytes in 4 chars you need
* at least: @len * 3 / 4 bytes.
* at least: (@len / 4) * 3 + 3 bytes (+ 3 may be needed in case of non-zero
* state).
*
* Return value: The number of bytes of output that was written
*
@ -358,7 +366,8 @@ g_base64_decode (const gchar *text,
gsize *out_len)
{
guchar *ret;
gint input_length, state = 0;
gsize input_length;
gint state = 0;
guint save = 0;
g_return_val_if_fail (text != NULL, NULL);
@ -368,7 +377,9 @@ g_base64_decode (const gchar *text,
g_return_val_if_fail (input_length > 1, NULL);
ret = g_malloc0 (input_length * 3 / 4);
/* We can use a smaller limit here, since we know the saved state is 0,
+1 used to avoid calling g_malloc0(0), and hence retruning NULL */
ret = g_malloc0 ((input_length / 4) * 3 + 1);
*out_len = g_base64_decode_step (text, input_length, ret, &state, &save);