gnu: gdk-pixbuf: Fix CVE-2020-29385.

* gnu/packages/patches/gdk-pixbuf-CVE-2020-29385.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/gtk.scm (gdk-pixbuf)[replacement]: New field.
(gdk-pixbuf/fixed): New variable.
(gdk-pixbuf+svg): Use package/inherit.

1 files changed, 53 insertions, 0 deletions

diff --git a/gnu/packages/patches/gdk-pixbuf-CVE-2020-29385.patch b/gnu/packages/patches/gdk-pixbuf-CVE-2020-29385.patch
new file mode 100644
index 0000000000..e6ac4de00b
--- /dev/null
+++ b/gnu/packages/patches/gdk-pixbuf-CVE-2020-29385.patch
@@ -0,0 +1,53 @@
+Fix CVE-2020-29385.  Note that we omit the binary test file
+tests/test-images/fail/hang_114.gif from the following commit, to avoid
+requiring 'git' to apply the patch.
+
+
+From bdd3acbd48a575d418ba6bf1b32d7bda2fae1c81 Mon Sep 17 00:00:00 2001
+From: Robert Ancell <robert.ancell@canonical.com>
+Date: Mon, 30 Nov 2020 12:26:12 +1300
+Subject: [PATCH] gif: Fix LZW decoder accepting invalid LZW code.
+
+The code value after a reset wasn't being validated, which means we would
+accept invalid codes. This could cause an infinite loop in the decoder.
+
+Fixes CVE-2020-29385
+
+Fixes https://gitlab.gnome.org/GNOME/gdk-pixbuf/-/issues/164
+---
+ gdk-pixbuf/lzw.c                    |  13 +++++++------
+ tests/test-images/fail/hang_114.gif | Bin 0 -> 5561 bytes
+ 2 files changed, 7 insertions(+), 6 deletions(-)
+ create mode 100644 tests/test-images/fail/hang_114.gif
+
+diff --git a/gdk-pixbuf/lzw.c b/gdk-pixbuf/lzw.c
+index 9e052a6f7..105daf2b1 100644
+--- a/gdk-pixbuf/lzw.c
++++ b/gdk-pixbuf/lzw.c
+@@ -195,19 +195,20 @@ lzw_decoder_feed (LZWDecoder *self,
+                                 if (self->last_code != self->clear_code && self->code_table_size < MAX_CODES) {
+                                         if (self->code < self->code_table_size)
+                                                 add_code (self, self->code);
+-                                        else if (self->code == self->code_table_size)
++                                        else
+                                                 add_code (self, self->last_code);
+-                                        else {
+-                                                /* Invalid code received - just stop here */
+-                                                self->last_code = self->eoi_code;
+-                                                return output_length;
+-                                        }
+ 
+                                         /* When table is full increase code size */
+                                         if (self->code_table_size == (1 << self->code_size) && self->code_size < LZW_CODE_MAX)
+                                                 self->code_size++;
+                                 }
+ 
++                                /* Invalid code received - just stop here */
++                                if (self->code >= self->code_table_size) {
++                                        self->last_code = self->eoi_code;
++                                        return output_length;
++                                }
++
+                                 /* Convert codeword into indexes */
+                                 n_written += write_indexes (self, output + n_written, output_length - n_written);
+                         }