[evolution-data-server] Allocate large-enough buffer for g_base64_decode_step()

[Milan Crha <mcrha src gnome org>]

commit b0731961dca6ca2ee4a11b708545d58ff4948093
Author: Milan Crha <mcrha redhat com>
Date:   Tue Mar 2 12:26:09 2021 +0100

    Allocate large-enough buffer for g_base64_decode_step()

 src/camel/camel-mime-filter-basic.c | 8 ++------
 src/camel/camel-mime-utils.c        | 2 +-
 2 files changed, 3 insertions(+), 7 deletions(-)
---
diff --git a/src/camel/camel-mime-filter-basic.c b/src/camel/camel-mime-filter-basic.c
index b13276264..8187fabd4 100644
--- a/src/camel/camel-mime-filter-basic.c
+++ b/src/camel/camel-mime-filter-basic.c
@@ -83,8 +83,7 @@ mime_filter_basic_filter (CamelMimeFilter *mime_filter,
                g_return_if_fail (newlen <= (len + 2) * 2 + 62);
                break;
        case CAMEL_MIME_FILTER_BASIC_BASE64_DEC:
-               /* output can't possibly exceed the input size */
-               camel_mime_filter_set_size (mime_filter, len + 3, FALSE);
+               camel_mime_filter_set_size (mime_filter, (len * 3 / 4) + 3, FALSE);
                newlen = g_base64_decode_step (
                        in, len,
                        (guchar *) mime_filter->outbuf,
@@ -225,10 +224,7 @@ mime_filter_basic_complete (CamelMimeFilter *mime_filter,
                g_return_if_fail (newlen <= (len + 2) * 2 + 62);
                break;
        case CAMEL_MIME_FILTER_BASIC_BASE64_DEC:
-               /* Output can't possibly exceed the input size, but add 1,
-                  to make sure the mime_filter->outbuf will not be NULL,
-                  in case the input stream is empty. */
-               camel_mime_filter_set_size (mime_filter, len + 1, FALSE);
+               camel_mime_filter_set_size (mime_filter, (len * 3 / 4) + 3, FALSE);
                newlen = g_base64_decode_step (
                        in, len,
                        (guchar *) mime_filter->outbuf,
diff --git a/src/camel/camel-mime-utils.c b/src/camel/camel-mime-utils.c
index 3394707e2..31024f5d4 100644
--- a/src/camel/camel-mime-utils.c
+++ b/src/camel/camel-mime-utils.c
@@ -1186,7 +1186,7 @@ rfc2047_decode_word (const gchar *in,
        case 'B':
        case 'b':
                inptr += 2;
-               decoded = g_alloca (inend - inptr);
+               decoded = g_alloca (((inend - inptr) * 3 / 4) + 3);
                declen = g_base64_decode_step ((gchar *) inptr, inend - inptr, decoded, &state, &save);
                break;
        case 'Q':