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Fix OSS-Fuzz #454273637: UAF with printf optimization and const output #20261

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ndossche merged 2 commits into from
Oct 23, 2025
Merged

Fix OSS-Fuzz #454273637: UAF with printf optimization and const output #20261

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Fix OSS-Fuzz #454273637: UAF with printf optimization and const output
ndossche Oct 22, 2025
be0c643
assert
ndossche Oct 22, 2025
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8 changes: 8 additions & 0 deletions Zend/tests/oss_fuzz_454273637.phpt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,8 @@
--TEST--
OSS-Fuzz #454273637 (UAF with printf optimization and const output)
--FILE--
<?php
printf('%%');
?>
--EXPECT--
%
13 changes: 10 additions & 3 deletions Zend/zend_compile.c
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Original file line number Diff line number Diff line change
Expand Up @@ -5009,9 +5009,16 @@ static zend_result zend_compile_func_printf(znode *result, zend_ast_list *args)
* pass in the Zend Optimizer if the result of the printf() is in fact
* unused */
znode copy;
zend_emit_op_tmp(&copy, ZEND_COPY_TMP, &rope_result, NULL);
zend_emit_op(NULL, ZEND_ECHO, &rope_result, NULL);
zend_emit_op_tmp(result, ZEND_STRLEN, &copy, NULL);
if (rope_result.op_type != IS_CONST) {
/* Note: ZEND_COPY_TMP is only valid for TMPVAR. */
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@iluuu1994 iluuu1994 Oct 22, 2025

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Maybe ZEND_ASSERT(rope_result.op_type == IS_TMP_VAR);?

zend_emit_op_tmp(&copy, ZEND_COPY_TMP, &rope_result, NULL);
zend_emit_op(NULL, ZEND_ECHO, &rope_result, NULL);
zend_emit_op_tmp(result, ZEND_STRLEN, &copy, NULL);
} else {
zend_emit_op(NULL, ZEND_ECHO, &rope_result, NULL);
result->op_type = IS_CONST;
ZVAL_LONG(&result->u.constant, Z_STRLEN(rope_result.u.constant));
}

return SUCCESS;
}
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