From 0c77b4307df73217283a4aaf9313e1a33a0967ff Mon Sep 17 00:00:00 2001
From: Stanislav Malyshev <stas@php.net>
Date: Sun, 15 Mar 2020 17:26:00 -0700
Subject: [PATCH] Fixed bug #79282

---
 ext/exif/exif.c              |  7 ++++++-
 ext/exif/tests/bug79282.phpt | 15 +++++++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)
 create mode 100644 ext/exif/tests/bug79282.phpt

diff --git a/ext/exif/exif.c b/ext/exif/exif.c
index a63e0c1..b85ac19 100644
--- a/ext/exif/exif.c
+++ b/ext/exif/exif.c
@@ -3660,6 +3660,11 @@ static void exif_process_TIFF_in_JPEG(image_info_type *ImageInfo, char *CharBuf,
 {
 	unsigned exif_value_2a, offset_of_ifd;
 
+	if (length < 2) {
+		exif_error_docref(NULL EXIFERR_CC, ImageInfo, E_WARNING, "Missing TIFF alignment marker");
+		return;
+	}
+
 	/* set the thumbnail stuff to nothing so we can test to see if they get set up */
 	if (memcmp(CharBuf, "II", 2) == 0) {
 		ImageInfo->motorola_intel = 0;
@@ -3812,7 +3817,7 @@ static int exif_scan_JPEG_header(image_info_type *ImageInfo)
 			return FALSE;
 		}
 
-		sn = exif_file_sections_add(ImageInfo, marker, itemlen+1, NULL);
+		sn = exif_file_sections_add(ImageInfo, marker, itemlen, NULL);
 		Data = ImageInfo->file.list[sn].data;
 
 		/* Store first two pre-read bytes. */
diff --git a/ext/exif/tests/bug79282.phpt b/ext/exif/tests/bug79282.phpt
new file mode 100644
index 0000000..7b7e365
--- /dev/null
+++ b/ext/exif/tests/bug79282.phpt
@@ -0,0 +1,15 @@
+--TEST--
+Bug #79282: Use-of-uninitialized-value in exif
+--FILE--
+<?php
+
+var_dump(exif_read_data('data://image/jpeg;base64,/9jhAAlFeGlmAAAg'));
+
+?>
+--EXPECTF--
+Warning: exif_read_data(): Invalid TIFF alignment marker in %s on line %d
+
+Warning: exif_read_data(): File structure corrupted in %s on line %d
+
+Warning: exif_read_data(): Invalid JPEG file in %s on line %d
+bool(false)
-- 
1.8.3.1