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From 21a204147b16539b3eda3143b32844c49e29f4d4 Mon Sep 17 00:00:00 2001
From: Philip Withnall <pwithnall@endlessos.org>
Date: Thu, 17 Aug 2023 11:33:49 +0000
Subject: [PATCH] gvariant: Propagate trust when getting a child of a
serialised variant
If a variant is trusted, that means all its children are trusted, so
ensure that their checked offsets are set as such.
This allows a lot of the offset table checks to be avoided when getting
children from trusted serialised tuples, which speeds things up.
No unit test is included because this is just a performance fix. If
there are other slownesses, or regressions, in serialised `GVariant`
performance, the fuzzing setup will catch them like it did this one.
This change does reduce the time to run the oss-fuzz reproducer from 80s
to about 0.7s on my machine.
Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
Fixes: #2841
oss-fuzz#54314
CVE: CVE-2023-32636
Upstream-Status: Backport from [https://gitlab.gnome.org/GNOME/glib/-/commit/21a204147b16539b3eda3143b32844c49e29f4d4]
Signed-off-by: Siddharth Doshi <sdoshi@mvista.com>
---
glib/gvariant-core.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/glib/gvariant-core.c b/glib/gvariant-core.c
index 1b9d5cc..ed57c70 100644
--- a/glib/gvariant-core.c
+++ b/glib/gvariant-core.c
@@ -1173,8 +1173,8 @@ g_variant_get_child_value (GVariant *value,
child->contents.serialised.bytes =
g_bytes_ref (value->contents.serialised.bytes);
child->contents.serialised.data = s_child.data;
- child->contents.serialised.ordered_offsets_up_to = s_child.ordered_offsets_up_to;
- child->contents.serialised.checked_offsets_up_to = s_child.checked_offsets_up_to;
+ child->contents.serialised.ordered_offsets_up_to = (value->state & STATE_TRUSTED) ? G_MAXSIZE : s_child.ordered_offsets_up_to;
+ child->contents.serialised.checked_offsets_up_to = (value->state & STATE_TRUSTED) ? G_MAXSIZE : s_child.checked_offsets_up_to;
return child;
}
--
2.24.4
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