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Fix GH-15980: Signed integer overflow in main/streams/streams.c #15989

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Fix GH-15980: Signed integer overflow in main/streams/streams.c #15989

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ff09d9a
Fix GH-15980: Signed integer overflow in main/streams/streams.c
cmb69 Sep 22, 2024
c535480
see what actually happens
cmb69 Sep 23, 2024
e90b6d0
Adapt test case to our findings
cmb69 Sep 23, 2024
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11 changes: 11 additions & 0 deletions ext/standard/tests/streams/gh15980.phpt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,11 @@
--TEST--
GH-15980 (Signed integer overflow in main/streams/streams.c)
--FILE--
<?php
$s = fopen(__FILE__, "r");
fseek($s, 1);
fseek($s, PHP_INT_MAX, SEEK_CUR);
var_dump(ftell($s) > 1);
?>
--EXPECT--
bool(true)
9 changes: 7 additions & 2 deletions main/streams/streams.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1354,8 +1354,13 @@ PHPAPI int _php_stream_seek(php_stream *stream, zend_off_t offset, int whence)

switch(whence) {
case SEEK_CUR:
offset = stream->position + offset;
whence = SEEK_SET;
ZEND_ASSERT(stream->position >= 0);
if (UNEXPECTED(offset > ZEND_LONG_MAX - stream->position)) {
offset = ZEND_LONG_MAX;
} else {
Comment on lines +1358 to +1360
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Long term we probably should warn about those large offsets

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@cmb69 cmb69 Sep 22, 2024 •
edited
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Yeah, although it's somewhat hard to determine what is too large. Something like ZEND_LONG_MAX - chunk size may work. (I'm mostly thinking about 32bit systems.)

offset = stream->position + offset;
}
whence = SEEK_SET;
break;
}
ret = stream->ops->seek(stream, offset, whence, &stream->position);
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