Brandon Nesterenko bf0aa99aeb MDEV-34237: On Startup: UBSAN: runtime error: call to function MDL_lock::lf_hash_initializer lf_hash_insert through pointer to incorrect function type 'void (*)(st_lf_hash *, void *, const void *)' ...

A few different incorrect function type UBSAN issues have been
grouped into this patch.

The only real potentially undefined behavior is an error about
show_func_mutex_instances_lost, which when invoked in
sql_show.cc::show_status_array(), puts 5 arguments onto the stack;
however, the implementing function only actually has 3 parameters (so
only 3 would be popped). This was fixed by adding in the remaining
parameters to satisfy the type mysql_show_var_func.

The rest of the findings are pointer type mismatches that wouldn't
lead to actual undefined behavior. The lf_hash_initializer function
type definition is

typedef void (*lf_hash_initializer)(LF_HASH *hash, void *dst, const void *src);

but the MDL_lock and table cache's implementations of this function
do not have that signature. The MDL_lock has specific MDL object
parameters:

static void lf_hash_initializer(LF_HASH *hash __attribute__((unused)),
                                MDL_lock *lock, MDL_key *key_arg)

and the table cache has specific TDC parameters:

static void tdc_hash_initializer(LF_HASH *,
                                 TDC_element *element, LEX_STRING *key)

leading to UBSAN runtime errors when invoking these functions.

This patch fixes these type mis-matches by changing the
implementing functions to use void * and const void * for their
respective parameters, and later casting them to their expected
type in the function body.

Note too the functions tdc_hash_key and tc_purge_callback had
a similar problem to tdc_hash_initializer and was fixed
similarly.

Reviewed By:
============
Sergei Golubchik <serg@mariadb.com>

2024-06-08 19:59:59 -06:00

16 KiB

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