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-rw-r--r--test/clip-double-free.c87
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diff --git a/test/clip-double-free.c b/test/clip-double-free.c
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+/*
+ * Copyright © 2011 Uli Schlachter
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy,
+ * modify, merge, publish, distribute, sublicense, and/or sell copies
+ * of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ * Author: Uli Schlachter <psychon@znc.in>
+ */
+
+/*
+ * This test wants to hit the following double free:
+ *
+ * ==10517== Invalid free() / delete / delete[]
+ * ==10517== at 0x4C268FE: free (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
+ * ==10517== by 0x87FBE80: _cairo_clip_destroy (cairo-clip.c:136)
+ * ==10517== by 0x87FE520: _cairo_clip_intersect_boxes.part.1 (cairo-clip-private.h:92)
+ * ==10517== by 0x87FE79F: _cairo_clip_intersect_rectilinear_path (cairo-clip-boxes.c:266)
+ * ==10517== by 0x87FC29B: _cairo_clip_intersect_path.part.3 (cairo-clip.c:242)
+ * ==10517== by 0x8809C3A: _cairo_gstate_clip (cairo-gstate.c:1518)
+ * ==10517== by 0x8802E40: _cairo_default_context_clip (cairo-default-context.c:1048)
+ * ==10517== by 0x87FA2C6: cairo_clip (cairo.c:2380)
+ * ==10517== Address 0x18d44cb0 is 0 bytes inside a block of size 32 free'd
+ * ==10517== at 0x4C268FE: free (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
+ * ==10517== by 0x87FE506: _cairo_clip_intersect_boxes.part.1 (cairo-clip-boxes.c:295)
+ * ==10517== by 0x87FE79F: _cairo_clip_intersect_rectilinear_path (cairo-clip-boxes.c:266)
+ * ==10517== by 0x87FC29B: _cairo_clip_intersect_path.part.3 (cairo-clip.c:242)
+ * ==10517== by 0x8809C3A: _cairo_gstate_clip (cairo-gstate.c:1518)
+ * ==10517== by 0x8802E40: _cairo_default_context_clip (cairo-default-context.c:1048)
+ * ==10517== by 0x87FA2C6: cairo_clip (cairo.c:2380)
+ *
+ * _cairo_clip_intersect_boxes() is called with clip->num_boxes != 0. It then
+ * calls _cairo_boxes_init_for_array (&clip_boxes, clip->boxes, clip->num_boxes)
+ * and free (clip->boxes), stealing the clip's boxes, but leaving a dangling
+ * pointer behind.
+ * Because this code already intersected the existing boxes and the new ones, we
+ * now have num_boxes == 0. This means that _cairo_clip_set_all_clipped() gets
+ * called and tries to free the clip's boxes again.
+ */
+
+#include "cairo-test.h"
+
+static cairo_test_status_t
+draw (cairo_t *cr, int width, int height)
+{
+ cairo_set_fill_rule (cr, CAIRO_FILL_RULE_EVEN_ODD);
+
+ /* To hit this bug, we first need a clip with
+ * clip->boxes != clip->embedded_boxes.
+ */
+ cairo_rectangle (cr, 0, 0, 2, 2);
+ cairo_rectangle (cr, 0, 0, 1, 1);
+ cairo_clip (cr);
+
+ /* Then we have to intersect this with a rectilinear path which results in
+ * all clipped. This path must consist of at least two boxes or we will hit
+ * a different code path.
+ */
+ cairo_rectangle (cr, 10, 10, 2, 2);
+ cairo_rectangle (cr, 10, 10, 1, 1);
+ cairo_clip (cr);
+
+ return CAIRO_TEST_SUCCESS;
+}
+
+CAIRO_TEST (clip_double_free,
+ "Test a double free bug in the clipping code",
+ "clip", /* keywords */
+ NULL, /* requirements */
+ 0, 0,
+ NULL, draw)