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Fix heap overflow when a read filter changes the stream's chunk size #24163

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Fix heap overflow when a read filter changes the stream's chunk size #24163

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39 changes: 39 additions & 0 deletions ext/standard/tests/streams/stream_set_chunk_size_in_read_filter.phpt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,39 @@
--TEST--
stream_set_chunk_size() called by a read filter
--FILE--
<?php
class Grow extends php_user_filter {
private int $seen = 0;

public function filter($in, $out, &$consumed, bool $closing): int {
stream_set_chunk_size($this->stream, 4000000);

while ($bucket = stream_bucket_make_writeable($in)) {
$consumed += $bucket->datalen;
$this->seen += $bucket->datalen;
}

if ($closing) {
stream_bucket_append($out, stream_bucket_new($this->stream, (string) $this->seen));
return PSFS_PASS_ON;
}

return PSFS_FEED_ME;
}
}

stream_filter_register('grow', 'Grow');

$file = __DIR__ . '/stream_set_chunk_size_in_read_filter.tmp';
file_put_contents($file, str_repeat('x', 65536));

$handle = fopen($file, 'r');
stream_filter_append($handle, 'grow', STREAM_FILTER_READ);
var_dump(fread($handle, 4096));
?>
--CLEAN--
<?php
@unlink(__DIR__ . '/stream_set_chunk_size_in_read_filter.tmp');
?>
--EXPECT--
string(5) "65536"
7 changes: 4 additions & 3 deletions main/streams/streams.c
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Original file line number Diff line number Diff line change
Expand Up @@ -565,13 +565,14 @@ PHPAPI zend_result _php_stream_fill_read_buffer(php_stream *stream, size_t size)
bool old_eof = stream->eof;

if (stream->readfilters.head) {
size_t to_read_now = MIN(size, stream->chunk_size);
const size_t chunk_size = stream->chunk_size;
size_t to_read_now = MIN(size, chunk_size);
char *chunk_buf;
php_stream_bucket_brigade brig_in = { NULL, NULL }, brig_out = { NULL, NULL };
php_stream_bucket_brigade *brig_inp = &brig_in, *brig_outp = &brig_out, *brig_swap;

/* allocate a buffer for reading chunks */
chunk_buf = emalloc(stream->chunk_size);
chunk_buf = emalloc(chunk_size);

while (!stream->eof && (stream->writepos - stream->readpos < (zend_off_t)to_read_now)) {
ssize_t justread = 0;
Expand All @@ -581,7 +582,7 @@ PHPAPI zend_result _php_stream_fill_read_buffer(php_stream *stream, size_t size)
php_stream_filter *filter;

/* read a chunk into a bucket */
justread = stream->ops->read(stream, chunk_buf, stream->chunk_size);
justread = stream->ops->read(stream, chunk_buf, chunk_size);
if (justread < 0 && stream->writepos == stream->readpos) {
efree(chunk_buf);
retval = FAILURE;
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