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test: Add clip-double-free

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This test tries to exercise a double free bug in the clipping code.

My webkit-based browser recently crashed a lot. Here is the reason why.

Signed-off-by: Uli Schlachter <psychon@znc.in>
This commit is contained in:
Uli Schlachter 2011-10-09 09:26:28 +02:00
parent a419d00fbe
commit 4092e90be5
2 changed files with 88 additions and 0 deletions
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1
test/Makefile.sources
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@ -42,6 +42,7 @@ test_sources = \
clip-disjoint.c \
clip-disjoint-hatching.c \
clip-device-offset.c \
clip-double-free.c \
clip-draw-unbounded.c \
clip-empty.c \
clip-empty-group.c \

87
test/clip-double-free.c Normal file
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@ -0,0 +1,87 @@
/*
* 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)