| 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 02/13] 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 |
| |
| Upstream-Status: Backport [https://gitlab.gnome.org/GNOME/gdk-pixbuf/-/commit/bdd3acbd48a575d418ba6bf1b32d7bda2fae1c81] |
| CVE: CVE-2020-29385 |
| Signed-off-by: Chee Yang Lee <chee.yang.lee@intel.com> |
| |
| --- |
| gdk-pixbuf/lzw.c | 13 +++++++------ |
| 1 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); |
| } |
| -- |
| 2.25.1 |
| |