Fix CVE-2017-7544:

https://sourceforge.net/p/libexif/bugs/130/
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-7544

Patch copied from upstream bug tracker:

https://sourceforge.net/p/libexif/bugs/130/#489a

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;
+			}
 		}
 	}
 
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<tr><td><span title='2018-03-23 04:40:08 -0400'>2018-03-23</span></td><td><a href='/guix/commit/gnu/packages/apr.scm?id=3d77ecfed4aab76fbd1a4b6718e44f42f482a70b'>gnu: apr-util: Use invoke.</a><span class='msg-avail'>...</span></td><td>Mark H Weaver</td></tr>
<tr><td><span title='2017-10-30 21:46:18 -0400'>2017-10-30</span></td><td><a href='/guix/commit/gnu/packages/apr.scm?id=b275cd22d47a42098f465ca30aee24fdc6e23826'>gnu: apr-util: Update to 1.6.1 [fixes CVE-2017-12618].</a><span class='msg-avail'>...</span></td><td>Leo Famulari</td></tr>
<tr><td><span title='2017-10-30 21:46:18 -0400'>2017-10-30</span></td><td><a href='/guix/commit/gnu/packages/apr.scm?id=b614c480178dd751c8bc5713b2052ecda29918d1'>gnu: apr: Update to 1.6.3 [fixes CVE-2017-12613].</a><span class='msg-avail'>...</span></td><td>Leo Famulari</td></tr>
<tr><td><span title='2017-09-20 20:58:04 -0400'>2017-09-20</span></td><td><a href='/guix/commit/gnu/packages/apr.scm?id=dc1d3cdef70f0e3c047c229c2a0e561d1f47bde8'>gnu: Use 'modify-phases' syntax.</a><span class='msg-avail'>...</span></td><td>Kei Kebreau</td></tr>