CVE-2024-44939 jfs: fix null ptr deref in dtInsertEntry

In the Linux kernel, the following vulnerability has been resolved: jfs: fix null ptr deref in dtInsertEntry syzbot reported general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 1 PREEMPT SMP KASAN PTI KASAN: null-ptr-deref in range...