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Fix GH-20620: bzcompress() overflow on large source size. #20621

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Fix GH-20620: bzcompress() overflow on large source size. #20621

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9 changes: 8 additions & 1 deletion ext/bz2/bz2.c
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Original file line number Diff line number Diff line change
Expand Up @@ -455,11 +455,18 @@ PHP_FUNCTION(bzcompress)
RETURN_THROWS();
}

size_t chunk_len = source_len + (0.01 * source_len) + 600;

if (chunk_len < source_len || chunk_len > UINT_MAX) {
zend_argument_value_error(1, "must be less than or equal to %lu", UINT_MAX);
RETURN_THROWS();
}

/* Assign them to easy to use variables, dest_len is initially the length of the data
+ .01 x length of data + 600 which is the largest size the results of the compression
could possibly be, at least that's what the libbz2 docs say (thanks to jeremy@nirvani.net
for pointing this out). */
dest_len = (unsigned int) (source_len + (0.01 * source_len) + 600);
dest_len = (unsigned int) chunk_len;

/* Allocate the destination buffer */
dest = zend_string_alloc(dest_len, 0);
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18 changes: 18 additions & 0 deletions ext/bz2/tests/gh20620.phpt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,18 @@
--TEST--
Bug GH-20620 (bzcompress with large source)
--EXTENSIONS--
bz2
--SKIPIF--
<?php if (PHP_INT_SIZE != 8) die('skip this test is for 64bit platforms only'); ?>
--INI--
memory_limit=-1
--FILE--
<?php
try {
bzcompress(str_repeat('1', 4295163906));
} catch (\ValueError $e) {
echo $e->getMessage(), PHP_EOL;
}
?>
--EXPECTF--
bzcompress(): Argument #1 ($data) must be less than or equal to %d
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