Fix memory leak found by GCC static analyzer

GCC 12.1.1_p20220625's -fanalyzer found and reported this.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Damian Szuberski <szuberskidamian@gmail.com>
Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Closes #13975