fix oob read on malformed length field in dba flatfile handler#22266
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alhudz wants to merge 2 commits into
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fix oob read on malformed length field in dba flatfile handler#22266alhudz wants to merge 2 commits into
alhudz wants to merge 2 commits into
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Girgias
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Jun 18, 2026
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| if (num >= buf_size) { | ||
| if (num > SIZE_MAX - FLATFILE_BLOCK_SIZE) { | ||
| break; | ||
| } | ||
| buf_size = num + FLATFILE_BLOCK_SIZE; | ||
| buf = erealloc(buf, buf_size); | ||
| } |
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Considering how often this is repeated, maybe a macro would make sense ?
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Done. Folded the parse-and-grow into a FLATFILE_GROW_BUF() macro that yields true when the length would overflow, so the break stays visible at each call site and the eight copies collapse to one. dba_flatfile.phpt, the creation matrix and the new regression test still pass.
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A flatfile opened read-only parses an attacker-controlled record length, and a negative value overruns the read buffer.
numis asize_tbut is assigned fromatoi(buf), so a length line of-1becomesSIZE_MAX.buf_size = num + FLATFILE_BLOCK_SIZE, which wraps to a tiny value andereallocshrinksbuf.php_stream_read(dba->fp, buf, num)then reads the rest of the file (numis stillSIZE_MAX) into the small buffer.repro:file_put_contents('x', "-1\n" . str_repeat('A', 200000)); $db = dba_open('x', 'r', 'flatfile'); dba_firstkey($db);expected:bool(false)actual:zend_mm_heap corrupted(SIGABRT)Reachable from
dba_firstkey/dba_nextkey/dba_fetch/dba_exists/dba_delete. The same idiom is repeated inflatfile_delete,flatfile_findkey,flatfile_firstkeyandflatfile_nextkey, so the guard goes in each. Added a regression test.