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Fix GH-16411: gmp_export() can cause overflow #16418

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Fix GH-16411: gmp_export() can cause overflow #16418

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4000ee7
Fix GH-16411: gmp_export() can cause overflow
cmb69 Oct 13, 2024
5f4e65c
Support test on 32bit too
cmb69 Oct 13, 2024
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10 changes: 8 additions & 2 deletions ext/gmp/gmp.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1002,8 +1002,14 @@ ZEND_FUNCTION(gmp_export)
if (mpz_sgn(gmpnumber) == 0) {
RETVAL_EMPTY_STRING();
} else {
size_t bits_per_word = size * 8;
size_t count = (mpz_sizeinbase(gmpnumber, 2) + bits_per_word - 1) / bits_per_word;
ZEND_ASSERT(size > 0);
size_t size_in_base_2 = mpz_sizeinbase(gmpnumber, 2);
if (size > ZEND_LONG_MAX / 4 || size_in_base_2 > SIZE_MAX - (size_t) size * 8 + 1) {
zend_argument_value_error(2, "is too large for argument #1 ($num)");
RETURN_THROWS();
}
size_t bits_per_word = (size_t) size * 8;
size_t count = (size_in_base_2 + bits_per_word - 1) / bits_per_word;

zend_string *out_string = zend_string_safe_alloc(count, size, 0, 0);
mpz_export(ZSTR_VAL(out_string), NULL, order, size, endian, 0, gmpnumber);
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11 changes: 11 additions & 0 deletions ext/gmp/tests/gh16411.phpt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,11 @@
--TEST--
GH-16411 (gmp_export() can cause overflow)
--EXTENSIONS--
gmp
--FILE--
<?php
gmp_export("-9223372036854775808", PHP_INT_MAX, PHP_INT_MIN);
?>
--EXPECTF--
Fatal error: Uncaught ValueError: gmp_export(): Argument #2 ($word_size) is too large for argument #1 ($num) in %s:%d
%A
Comment on lines +5 to +11
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You could try/catch the ValueError and have the output just be an EXPECT section, but that is minor nit.

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