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Bug #55098 SimpleXML iteration produces infinite loop
Submitted: 2011-07-01 04:23 UTC Modified: 2015-09-04 14:46 UTC
Avg. Score:4.4 ± 0.7
Reproduced:19 of 19 (100.0%)
Same Version:9 (47.4%)
Same OS:10 (52.6%)
From: karl dot raab at elements dot at Assigned:
Status: Verified Package: SimpleXML related
PHP Version: 5.3.6 OS: Linux
Private report: No CVE-ID: None
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 [2011-07-01 04:23 UTC] karl dot raab at elements dot at
see the test script. 

inside the foreach-loop the call of e.g. $nodes->asXml() will reset the iteration 
to the beginning and therefore the loop will forever remain on the second element.

this may be related to bug #50670 and #51846

greets, karl

Test script:
$xmlString = "<root><a><b>1</b><b>2</b><b>3</b></a></root>";
$xml = simplexml_load_string($xmlString);

$nodes = $xml->a->b;
foreach ($nodes as $nodeData) {
    echo "nodeData: " . $nodeData . "\n";

    //the following code will break the iteration on the second element and resets the pointer
    //happens by any of these methods
    $xml = $nodes->asXml();

Expected result:
nodeData: 1
nodeData: 2
nodeData: 3

Actual result:
nodeData: 1
nodeData: 2
nodeData: 2
nodeData: 2
nodeData: 2
nodeData: 2
nodeData: 2
nodeData: 2
nodeData: 2
nodeData: 2
and so on...


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 [2011-07-01 05:16 UTC] karl dot raab at elements dot at
already noticed an orphan comment in the test script. 
just ignore the line "//iteration_breaker($nodes);" 

cheers, karl
 [2015-09-04 14:46 UTC]
-Status: Open +Status: Verified
 [2015-09-04 14:46 UTC]
Even simpler reproduce script:

    $xml = simplexml_load_string('<root><a>1</a><a>2</a></root>');
    $as = $xml->a;
    foreach ($as as $a) {

Generally, when iterating over SimpleXMLElement, you must not
access this object inside the loop. That may may work in some
cases, but usually accessing a SimpleXMLElement calls
php_sxe_get_first_node()[1], which calls php_sxe_reset_iterator()[2],
when the element is currently iterated over. Obviously, this leads
to an infinite loop.

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[2] <>
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