main/libexif: security fix (CVE-2017-7544)

Fixes #9521

main/libexif/APKBUILD

 # Maintainer: Natanael Copa <ncopa@alpinelinux.org>
 pkgname=libexif
 pkgver=0.6.21
-pkgrel=2
+pkgrel=3
 pkgdesc="A library to parse an EXIF file and read the data from those tags"
 url="https://sourceforge.net/projects/libexif"
 arch="all"
@@ -9,7 +9,13 @@ license="LGPL-2.0+"
 subpackages="$pkgname-dev $pkgname-doc"
 depends=
 makedepends=
-source="https://downloads.sf.net/sourceforge/$pkgname/$pkgname-$pkgver.tar.bz2"
+source="https://downloads.sf.net/sourceforge/$pkgname/$pkgname-$pkgver.tar.bz2
+	CVE-2017-7544.patch
+	"
+
+# secfixes
+#   0.6.21-r3:
+#     - CVE-2017-7544
 
 prepare() {
 	cd "$builddir"
@@ -35,4 +41,5 @@ package() {
 	cd "$builddir"
 	make DESTDIR="$pkgdir" install
 }
-sha512sums="4e0fe2abe85d1c95b41cb3abe1f6333dc3a9eb69dba106a674a78d74a4d5b9c5a19647118fa1cc2d72b98a29853394f1519eda9e2889eb28d3be26b21c7cfc35  libexif-0.6.21.tar.bz2"
+sha512sums="4e0fe2abe85d1c95b41cb3abe1f6333dc3a9eb69dba106a674a78d74a4d5b9c5a19647118fa1cc2d72b98a29853394f1519eda9e2889eb28d3be26b21c7cfc35  libexif-0.6.21.tar.bz2
+5475c9e0f4a05448a571077d24d545cfaa0a7b15978345e92440107770077158b994fc0c785a81bb95ad6b409929c4c516c6e002cd65c9d35eb0e91161750e48  CVE-2017-7544.patch"

main/libexif/CVE-2017-7544.patch

+Index: libexif/exif-data.c
+===================================================================
+RCS file: /cvsroot/libexif/libexif/libexif/exif-data.c,v
+retrieving revision 1.131
+diff -u -r1.131 exif-data.c
+--- a/libexif/exif-data.c	12 Jul 2012 17:28:26 -0000	1.131
++++ b/libexif/exif-data.c	25 Jul 2017 21:34:06 -0000
+@@ -255,6 +255,12 @@
+ 			exif_mnote_data_set_offset (data->priv->md, *ds - 6);
+ 			exif_mnote_data_save (data->priv->md, &e->data, &e->size);
+ 			e->components = e->size;
++			if (exif_format_get_size (e->format) != 1) {
++				/* e->format is taken from input code,
++				 * but we need to make sure it is a 1 byte
++				 * entity due to the multiplication below. */
++				e->format = EXIF_FORMAT_UNDEFINED;
++			}
+ 		}
+ 	}
+