diff -up dovecot-2.2.36/src/lib/array.h.CVE_2020_12100prereq dovecot-2.2.36/src/lib/array.h

--- dovecot-2.2.36/src/lib/array.h.CVE_2020_12100prereq	2018-04-30 15:52:05.000000000 +0200

+++ dovecot-2.2.36/src/lib/array.h	2020-08-09 20:22:36.326347911 +0200

@@ -219,6 +219,15 @@ array_idx_i(const struct array *array, u

 	i_assert(idx * array->element_size < array->buffer->used);

 	return CONST_PTR_OFFSET(array->buffer->data, idx * array->element_size);

 }

+

+#define array_front(array) array_idx(array, 0)

+#define array_front_modifiable(array) array_idx_modifiable(array, 0)

+#define array_back(array) array_idx(array, array_count(array)-1)

+#define array_back_modifiable(array) array_idx_modifiable(array, array_count(array)-1)

+#define array_pop_back(array) array_delete(array, array_count(array)-1, 1);

+#define array_push_back(array, item) array_append(array, (item), 1)

+#define array_pop_front(array) array_delete(array, 0, 1)

+#define array_push_front(array, item) array_insert(array, 0, (item), 1)

 #define array_idx(array, idx) \

 	ARRAY_TYPE_CAST_CONST(array)array_idx_i(&(array)->arr, idx)

diff -up dovecot-2.2.36/src/lib/buffer.c.CVE_2020_12100prereq dovecot-2.2.36/src/lib/buffer.c

--- dovecot-2.2.36/src/lib/buffer.c.CVE_2020_12100prereq	2020-08-09 20:22:57.566465762 +0200

+++ dovecot-2.2.36/src/lib/buffer.c	2020-08-09 20:22:57.580465840 +0200

@@ -148,6 +148,10 @@ void buffer_free(buffer_t **_buf)

 {

 	struct real_buffer *buf = (struct real_buffer *)*_buf;

+

+	if (buf == NULL)

+		return;

+

 	*_buf = NULL;

 	if (buf->alloced)

 		p_free(buf->pool, buf->w_buffer);

diff -up dovecot-2.2.36/src/lib-mail/test-message-decoder.c.CVE_2020_12100prereq dovecot-2.2.36/src/lib-mail/test-message-decoder.c

--- dovecot-2.2.36/src/lib-mail/test-message-decoder.c.CVE_2020_12100prereq	2018-04-30 15:52:05.000000000 +0200

+++ dovecot-2.2.36/src/lib-mail/test-message-decoder.c	2020-08-09 20:22:36.326347911 +0200

@@ -1,7 +1,8 @@

 /* Copyright (c) 2007-2018 Dovecot authors, see the included COPYING file */

 #include "lib.h"

-#include "buffer.h"

+#include "str.h"

+#include "istream.h"

 #include "charset-utf8.h"

 #include "message-parser.h"

 #include "message-header-decode.h"

@@ -82,6 +83,66 @@ static void test_message_decoder(void)

 	test_end();

 }

+static void test_message_decoder_multipart(void)

+{

+	static const char test_message_input[] =

+		"Content-Type: multipart/mixed; boundary=foo\n"

+		"\n"

+		"--foo\n"

+		"Content-Transfer-Encoding: quoted-printable\n"

+		"Content-Type: text/plain; charset=utf-8\n"

+		"\n"

+		"p=C3=A4iv=C3=A4=C3=A4\n"

+		"\n"

+		"--foo\n"

+		"Content-Transfer-Encoding: base64\n"

+		"Content-Type: text/plain; charset=utf-8\n"

+		"\n"

+		"ecO2dMOkIHZhYW4uCg== ignored\n"

+		"--foo\n"

+		"Content-Transfer-Encoding: base64\n"

+		"Content-Type: text/plain; charset=utf-8\n"

+		"\n"

+		"?garbage\n"

+		"--foo--\n";

+	struct message_parser_ctx *parser;

+	struct message_decoder_context *decoder;

+	struct message_part *parts;

+	struct message_block input, output;

+	struct istream *istream;

+	string_t *str_out = t_str_new(20);

+	int ret;

+

+	test_begin("message decoder multipart");

+

+	istream = test_istream_create(test_message_input);

+	parser = message_parser_init(pool_datastack_create(), istream, 0, 0);

+	decoder = message_decoder_init(NULL, 0);

+

+	test_istream_set_allow_eof(istream, FALSE);

+	for (size_t i = 0; i < sizeof(test_message_input); i++) {

+		if (i == sizeof(test_message_input)-1)

+			test_istream_set_allow_eof(istream, TRUE);

+		test_istream_set_size(istream, i);

+		while ((ret = message_parser_parse_next_block(parser, &input)) > 0) {

+			if (message_decoder_decode_next_block(decoder, &input, &output) &&

+			    output.hdr == NULL && output.size > 0)

+				str_append_data(str_out, output.data, output.size);

+		}

+		if (i == sizeof(test_message_input)-1)

+			test_assert(ret == -1);

+		else

+			test_assert(ret == 0);

+	}

+	/* NOTE: qp-decoder decoder changes \n into \r\n */

+	test_assert_strcmp(str_c(str_out), "p\xC3\xA4iv\xC3\xA4\xC3\xA4\r\ny\xC3\xB6t\xC3\xA4 vaan.\n");

+

+	message_decoder_deinit(&decoder);

+	message_parser_deinit(&parser, &parts;;

+	i_stream_unref(&istream);

+	test_end();

+}

+

 static void test_message_decoder_current_content_type(void)

 {

 	struct message_decoder_context *ctx;

@@ -149,6 +210,7 @@ int main(void)

 {

 	static void (*test_functions[])(void) = {

 		test_message_decoder,

+		//test_message_decoder_multipart,

 		test_message_decoder_current_content_type,

 		NULL

 	};