Fix CVE-2018-1000222:

https://github.com/libgd/libgd/issues/447
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-1000222

Patch copied from upstream source repository:

https://github.com/libgd/libgd/commit/4b1e18a00ce7c4b7e6919c3b3109a034393b805a

From 4b1e18a00ce7c4b7e6919c3b3109a034393b805a Mon Sep 17 00:00:00 2001
From: Mike Frysinger <vapier@gentoo.org>
Date: Sat, 14 Jul 2018 13:54:08 -0400
Subject: [PATCH] bmp: check return value in gdImageBmpPtr

Closes #447.

(cherry picked from commit ac16bdf2d41724b5a65255d4c28fb0ec46bc42f5)
---
 src/gd_bmp.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/src/gd_bmp.c b/src/gd_bmp.c
index ccafdcd..d625da1 100644
--- a/src/gd_bmp.c
+++ b/src/gd_bmp.c
@@ -48,6 +48,8 @@ static int bmp_read_4bit(gdImagePtr im, gdIOCtxPtr infile, bmp_info_t *info, bmp
 static int bmp_read_8bit(gdImagePtr im, gdIOCtxPtr infile, bmp_info_t *info, bmp_hdr_t *header);
 static int bmp_read_rle(gdImagePtr im, gdIOCtxPtr infile, bmp_info_t *info);
 
+static int _gdImageBmpCtx(gdImagePtr im, gdIOCtxPtr out, int compression);
+
 #define BMP_DEBUG(s)
 
 static int gdBMPPutWord(gdIOCtx *out, int w)
@@ -88,8 +90,10 @@ BGD_DECLARE(void *) gdImageBmpPtr(gdImagePtr im, int *size, int compression)
 	void *rv;
 	gdIOCtx *out = gdNewDynamicCtx(2048, NULL);
 	if (out == NULL) return NULL;
-	gdImageBmpCtx(im, out, compression);
-	rv = gdDPExtractData(out, size);
+	if (!_gdImageBmpCtx(im, out, compression))
+		rv = gdDPExtractData(out, size);
+	else
+		rv = NULL;
 	out->gd_free(out);
 	return rv;
 }
@@ -142,6 +146,11 @@ BGD_DECLARE(void) gdImageBmp(gdImagePtr im, FILE *outFile, int compression)
 		compression - whether to apply RLE or not.
 */
 BGD_DECLARE(void) gdImageBmpCtx(gdImagePtr im, gdIOCtxPtr out, int compression)
+{
+	_gdImageBmpCtx(im, out, compression);
+}
+
+static int _gdImageBmpCtx(gdImagePtr im, gdIOCtxPtr out, int compression)
 {
 	int bitmap_size = 0, info_size, total_size, padding;
 	int i, row, xpos, pixel;
@@ -149,6 +158,7 @@ BGD_DECLARE(void) gdImageBmpCtx(gdImagePtr im, gdIOCtxPtr out, int compression)
 	unsigned char *uncompressed_row = NULL, *uncompressed_row_start = NULL;
 	FILE *tmpfile_for_compression = NULL;
 	gdIOCtxPtr out_original = NULL;
+	int ret = 1;
 
 	/* No compression if its true colour or we don't support seek */
 	if (im->trueColor) {
@@ -326,6 +336,7 @@ BGD_DECLARE(void) gdImageBmpCtx(gdImagePtr im, gdIOCtxPtr out, int compression)
 		out_original = NULL;
 	}
 
+	ret = 0;
 cleanup:
 	if (tmpfile_for_compression) {
 #ifdef _WIN32
@@ -339,7 +350,7 @@ cleanup:
 	if (out_original) {
 		out_original->gd_free(out_original);
 	}
-	return;
+	return ret;
 }
 
 static int compress_row(unsigned char *row, int length)
-- 
2.18.0

