From 2ad1af5b1ee5934a5d66be506b85157facc73a46 Mon Sep 17 00:00:00 2001 From: Matthias Clasen Date: Thu, 12 Mar 2009 13:30:55 +0000 Subject: [PATCH] Avoid integer overflows in the base64 functions. Fixes CVE-2008-4316 2009-03-12 Matthias Clasen * glib/gbase64.c: Avoid integer overflows in the base64 functions. Fixes CVE-2008-4316 svn path=/trunk/; revision=7973 --- ChangeLog | 5 +++++ glib/gbase64.c | 25 ++++++++++++++++++------- 2 files changed, 23 insertions(+), 7 deletions(-) diff --git a/ChangeLog b/ChangeLog index d72e50f..f5eed17 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,8 @@ +2009-03-12 Matthias Clasen + + * glib/gbase64.c: Avoid integer overflows in the base64 + functions. Fixes CVE-2008-4316 + 2009-03-11 Stef Walter * glib/gchecksum.c: Document and guarantee hex digests will diff --git a/glib/gbase64.c b/glib/gbase64.c index 99adb85..bfdc76a 100644 --- a/glib/gbase64.c +++ b/glib/gbase64.c @@ -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); -- 2.7.4