Red Hat Bugzilla – Bug 88052
register_printf_function() forgets to clear table
Last modified: 2016-11-24 09:53:23 EST
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Description of problem:
Routine register_printf_function() in stdio-common/reg-printf.c forgets to clear
the table when allocating it, before inserting the first translation function.
The table is consulted for all format characters, not just those that use the
registered arginfo or functions. So if malloc() happens to return a block that
was used before, then parse_one_spec() will go wrong if the consulted slot has
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. Run testcase stdio-common/tst-printfsz.
2. Watch as parse_one_spec() examines the entry for 'g' which has not been
Actual Results: __printf_arginfo_table['g'] and __printf_function_table['g']
are used even though they have not been initialized. In the usual case,
malloc() without any preceding free() happens to return zeroed memory [as if
Expected Results: _printf_arginfo_table and __printf_function_table should be
initialized before use.
Fix: s/malloc/calloc/ in stdio-common/reg-printf.c line 49.
This could have been detected by running valgrind (or any other uninit memory
detector) when running the glibc testcases.
An errata has been issued which should help the problem described in this bug report.
This report is therefore being closed with a resolution of ERRATA. For more information
on the solution and/or where to find the updated files, please follow the link below. You may reopen
this bug report if the solution does not work for you.