100 lines
3.4 KiB
Diff
100 lines
3.4 KiB
Diff
From 94e49c2beda08a9898775845d93bb3b1412305e8 Mon Sep 17 00:00:00 2001
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From: Nils Philippsen <nils@redhat.com>
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Date: Thu, 30 Jun 2016 11:49:48 +0200
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Subject: [PATCH] patch: CVE-2016-4994
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Squashed commit of the following:
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commit 9b9acd64de207608ffa47d01ce60a5bdf973148e
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Author: Shmuel H <shmuelgimp@gmail.com>
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Date: Mon Jun 20 17:14:41 2016 +0300
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Bug 767873 - (CVE-2016-4994) Multiple Use-After-Free when parsing...
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...XCF channel and layer properties
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The properties PROP_ACTIVE_LAYER, PROP_FLOATING_SELECTION,
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PROP_ACTIVE_CHANNEL saves the current object pointer the @info
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structure. Others like PROP_SELECTION (for channel) and
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PROP_GROUP_ITEM (for layer) will delete the current object and create
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a new object, leaving the pointers in @info invalid (dangling).
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Therefore, if a property from the first type will come before the
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second, the result will be an UaF in the last lines of xcf_load_image
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(when it actually using the pointers from @info).
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I wasn't able to exploit this bug because that
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g_object_instance->c_class gets cleared by the last g_object_unref and
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GIMP_IS_{LAYER,CHANNEL} detects that and return FALSE.
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(cherry picked from commit 6d804bf9ae77bc86a0a97f9b944a129844df9395)
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(cherry picked from commit e82aaa4b4ee0703c879e35ea9321fff6be3e9b6f)
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---
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app/xcf/xcf-load.c | 29 +++++++++++++++++++++++++++++
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1 file changed, 29 insertions(+)
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diff --git a/app/xcf/xcf-load.c b/app/xcf/xcf-load.c
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index b180377..67cc6d4 100644
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--- a/app/xcf/xcf-load.c
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+++ b/app/xcf/xcf-load.c
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@@ -904,6 +904,18 @@ xcf_load_layer_props (XcfInfo *info,
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case PROP_GROUP_ITEM:
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{
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GimpLayer *group;
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+ gboolean is_active_layer;
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+
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+ /* We're going to delete *layer, Don't leave its pointers
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+ * in @info. After that, we'll restore them back with the
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+ * new pointer. See bug #767873.
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+ */
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+ is_active_layer = (*layer == info->active_layer);
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+ if (is_active_layer)
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+ info->active_layer = NULL;
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+
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+ if (*layer == info->floating_sel)
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+ info->floating_sel = NULL;
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group = gimp_group_layer_new (image);
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@@ -916,6 +928,13 @@ xcf_load_layer_props (XcfInfo *info,
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g_object_ref_sink (*layer);
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g_object_unref (*layer);
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*layer = group;
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+
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+ if (is_active_layer)
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+ info->active_layer = *layer;
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+
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+ /* Don't restore info->floating_sel because group layers
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+ * can't be floating selections
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+ */
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}
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break;
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@@ -986,6 +1005,12 @@ xcf_load_channel_props (XcfInfo *info,
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{
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GimpChannel *mask;
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+ /* We're going to delete *channel, Don't leave its pointer
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+ * in @info. See bug #767873.
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+ */
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+ if (*channel == info->active_channel)
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+ info->active_channel = NULL;
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+
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mask =
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gimp_selection_new (image,
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gimp_item_get_width (GIMP_ITEM (*channel)),
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@@ -1000,6 +1025,10 @@ xcf_load_channel_props (XcfInfo *info,
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*channel = mask;
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(*channel)->boundary_known = FALSE;
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(*channel)->bounds_known = FALSE;
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+
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+ /* Don't restore info->active_channel because the
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+ * selection can't be the active channel
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+ */
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}
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break;
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--
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2.5.5
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