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SakiTakamachiSakiTakamachi
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Fixed a bug where size_t underflows (php#16696)
fixes php#16262 closes php#16696
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‎NEWS

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Original file line numberDiff line numberDiff line change
@@ -5,6 +5,7 @@ PHP NEWS
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- BcMath:
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. Fixed bug GH-16265 (Added early return case when result is 0)
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(Saki Takamachi).
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. Fixed bug GH-16262 (Fixed a bug where size_t underflows) (Saki Takamachi).
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- Core:
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. Fixed bug GH-16574 (Incorrect error "undefined method" messages).

‎ext/bcmath/libbcmath/src/div.c

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Original file line numberDiff line numberDiff line change
@@ -434,7 +434,7 @@ bool bc_divide(bc_num numerator, bc_num divisor, bc_num *quot, size_t scale)
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numerator_bottom_extension -= scale_diff;
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} else {
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numerator_bottom_extension = 0;
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numeratorend -= scale_diff - numerator_bottom_extension;
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numeratorend -= scale_diff > numerator_top_extension ? scale_diff - numerator_top_extension : 0;
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}
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} else {
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numerator_bottom_extension += scale - numerator_scale;

‎ext/bcmath/tests/gh16262.phpt

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,158 @@
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--TEST--
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GH-16262 Stack buffer overflow in ext/bcmath/libbcmath/src/div.c:459
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--EXTENSIONS--
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bcmath
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--INI--
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bcmath.scale=0
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--FILE--
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<?php
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$scales = [
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null,
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0,
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1,
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2,
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3,
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4,
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5,
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];
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foreach ($scales as $scale) {
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echo '========== scale: ', $scale ?? 'null', " ==========\n";
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echo "1 / 1000:\n";
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var_dump(
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bcdiv('1', '1000', $scale),
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(new BcMath\Number('1'))->div('1000', $scale),
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);
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echo "1 / 2000:\n";
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var_dump(
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bcdiv('1', '2000', $scale),
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(new BcMath\Number('1'))->div('2000', $scale),
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);
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echo "\n";
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}
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?>
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--EXPECT--
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========== scale: null ==========
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1 / 1000:
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string(1) "0"
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object(BcMath\Number)#2 (2) {
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["value"]=>
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string(5) "0.001"
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["scale"]=>
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int(3)
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}
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1 / 2000:
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string(1) "0"
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object(BcMath\Number)#1 (2) {
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["value"]=>
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string(6) "0.0005"
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["scale"]=>
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int(4)
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}
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========== scale: 0 ==========
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1 / 1000:
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string(1) "0"
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object(BcMath\Number)#2 (2) {
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["value"]=>
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string(1) "0"
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["scale"]=>
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int(0)
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}
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1 / 2000:
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string(1) "0"
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object(BcMath\Number)#1 (2) {
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["value"]=>
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string(1) "0"
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["scale"]=>
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int(0)
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}
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========== scale: 1 ==========
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1 / 1000:
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string(3) "0.0"
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object(BcMath\Number)#2 (2) {
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["value"]=>
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string(3) "0.0"
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["scale"]=>
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int(1)
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}
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1 / 2000:
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string(3) "0.0"
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object(BcMath\Number)#1 (2) {
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["value"]=>
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string(3) "0.0"
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["scale"]=>
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int(1)
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}
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========== scale: 2 ==========
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1 / 1000:
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string(4) "0.00"
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object(BcMath\Number)#2 (2) {
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["value"]=>
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string(4) "0.00"
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["scale"]=>
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int(2)
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}
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1 / 2000:
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string(4) "0.00"
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object(BcMath\Number)#1 (2) {
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["value"]=>
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string(4) "0.00"
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["scale"]=>
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int(2)
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}
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========== scale: 3 ==========
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1 / 1000:
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string(5) "0.001"
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object(BcMath\Number)#2 (2) {
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["value"]=>
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string(5) "0.001"
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["scale"]=>
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int(3)
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}
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1 / 2000:
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string(5) "0.000"
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object(BcMath\Number)#1 (2) {
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["value"]=>
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string(5) "0.000"
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["scale"]=>
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int(3)
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}
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========== scale: 4 ==========
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1 / 1000:
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string(6) "0.0010"
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object(BcMath\Number)#2 (2) {
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["value"]=>
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string(6) "0.0010"
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["scale"]=>
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int(4)
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}
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1 / 2000:
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string(6) "0.0005"
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object(BcMath\Number)#1 (2) {
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["value"]=>
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string(6) "0.0005"
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["scale"]=>
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int(4)
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}
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========== scale: 5 ==========
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1 / 1000:
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string(7) "0.00100"
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object(BcMath\Number)#2 (2) {
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["value"]=>
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string(7) "0.00100"
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["scale"]=>
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int(5)
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}
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1 / 2000:
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string(7) "0.00050"
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object(BcMath\Number)#1 (2) {
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["value"]=>
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string(7) "0.00050"
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["scale"]=>
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int(5)
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}

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