gnu: ghostscript: Fix CVE-2020-15900.

* gnu/packages/patches/ghostscript-CVE-2020-15900.patch: New file.
* gnu/local.mk (dist_patch_DATA): Adjust accordingly.
* gnu/packages/ghostscript.scm (ghostscript)[source](patches): Add it.

1 files changed, 36 insertions, 0 deletions

diff --git a/gnu/packages/patches/ghostscript-CVE-2020-15900.patch b/gnu/packages/patches/ghostscript-CVE-2020-15900.patch
new file mode 100644
index 0000000000..b6658d7c7f
--- /dev/null
+++ b/gnu/packages/patches/ghostscript-CVE-2020-15900.patch
@@ -0,0 +1,36 @@
+Fix CVE-2020-15900.
+
+https://cve.circl.lu/cve/CVE-2020-15900
+https://artifex.com/security-advisories/CVE-2020-15900
+
+Taken from upstream:
+https://git.ghostscript.com/?p=ghostpdl.git;a=commitdiff;h=5d499272b95a6b890a1397e11d20937de000d31b
+
+diff --git a/psi/zstring.c b/psi/zstring.c
+--- a/psi/zstring.c
++++ b/psi/zstring.c
+@@ -142,13 +142,18 @@ search_impl(i_ctx_t *i_ctx_p, bool forward)
+     return 0;
+ found:
+     op->tas.type_attrs = op1->tas.type_attrs;
+-    op->value.bytes = ptr;
+-    r_set_size(op, size);
++    op->value.bytes = ptr;				/* match */
++    op->tas.rsize = size;				/* match */
+     push(2);
+-    op[-1] = *op1;
+-    r_set_size(op - 1, ptr - op[-1].value.bytes);
+-    op1->value.bytes = ptr + size;
+-    r_set_size(op1, count + (!forward ? (size - 1) : 0));
++    op[-1] = *op1;					/* pre */
++    op[-3].value.bytes = ptr + size;			/* post */
++    if (forward) {
++        op[-1].tas.rsize = ptr - op[-1].value.bytes;	/* pre */
++        op[-3].tas.rsize = count;			/* post */
++    } else {
++        op[-1].tas.rsize = count;			/* pre */
++        op[-3].tas.rsize -= count + size;		/* post */
++    }
+     make_true(op);
+     return 0;
+ }