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Allow zero length ranges in sanitization (#1617) 

Fixes fvar table sanitization where there are no named instance
by allowing zero length ranges starting from Null() address.

Fixes #1607
This commit is contained in:
Ebrahim Byagowi 2019-03-14 16:49:42 -07:00 committed by Michiharu Ariza
parent ee8719eaaf
commit 5bbe78a0f3
3 changed files with 25 additions and 14 deletions
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30
src/hb-machinery.hh
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@ -326,27 +326,29 @@ struct hb_sanitize_context_t :
} }
bool check_range (const void *base, bool check_range (const void *base,
unsigned int len) const unsigned int len) const
{ {
const char *p = (const char *) base; const char *p = (const char *) base;
bool ok = this->start <= p && bool ok = !len ||
p <= this->end && (this->start <= p &&
(unsigned int) (this->end - p) >= len && p <= this->end &&
this->max_ops-- > 0; (unsigned int) (this->end - p) >= len &&
this->max_ops-- > 0);
DEBUG_MSG_LEVEL (SANITIZE, p, this->debug_depth+1, 0, DEBUG_MSG_LEVEL (SANITIZE, p, this->debug_depth+1, 0,
"check_range [%p..%p] (%d bytes) in [%p..%p] -> %s", "check_range [%p..%p]"
p, p + len, len, " (%d bytes) in [%p..%p] -> %s",
this->start, this->end, p, p + len, len,
ok ? "OK" : "OUT-OF-RANGE"); this->start, this->end,
ok ? "OK" : "OUT-OF-RANGE");
return likely (ok); return likely (ok);
} }
template <typename T> template <typename T>
bool check_range (const T *base, bool check_range (const T *base,
unsigned int a, unsigned int a,
unsigned int b) const unsigned int b) const
{ {
return !hb_unsigned_mul_overflows (a, b) && return !hb_unsigned_mul_overflows (a, b) &&
this->check_range (base, a * b); this->check_range (base, a * b);
@ -354,9 +356,9 @@ struct hb_sanitize_context_t :
template <typename T> template <typename T>
bool check_range (const T *base, bool check_range (const T *base,
unsigned int a, unsigned int a,
unsigned int b, unsigned int b,
unsigned int c) const unsigned int c) const
{ {
return !hb_unsigned_mul_overflows (a, b) && return !hb_unsigned_mul_overflows (a, b) &&
this->check_range (base, a * b, c); this->check_range (base, a * b, c);

BIN
test/api/fonts/Zycon.ttf Normal file
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9
test/api/test-ot-face.c
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@ -110,12 +110,21 @@ test_ot_face_empty (void)
test_face (hb_face_get_empty (), 0); test_face (hb_face_get_empty (), 0);
} }
static void
test_ot_var_axis_on_zero_named_instance ()
{
hb_face_t *face = hb_test_open_font_file ("fonts/Zycon.ttf");
g_assert (hb_ot_var_get_axis_count (face));
hb_face_destroy (face);
}
int int
main (int argc, char **argv) main (int argc, char **argv)
{ {
hb_test_init (&argc, &argv); hb_test_init (&argc, &argv);
hb_test_add (test_ot_face_empty); hb_test_add (test_ot_face_empty);
hb_test_add (test_ot_var_axis_on_zero_named_instance);
return hb_test_run(); return hb_test_run();
} }