CVE-2025-21881 uprobes: Reject the shared zeropage in uprobe_write_opcode()

In the Linux kernel, the following vulnerability has been resolved: uprobes: Reject the shared zeropage in uprobewriteopcode We triggered the following crash in syzkaller tests: BUG: Bad page state in process syz.7.38 pfn:1eff3 page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0...