From Bugzilla Helper:
User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.0.0) Gecko/20020529

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
non-zero garbage.

Version-Release number of selected component (if applicable):
glibc-2.3.2-11.9

How reproducible:
Always

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
initialized.
3.
    

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
calloc()].

Expected Results:  _printf_arginfo_table and __printf_function_table should be
initialized before use.

Additional info:

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.