CVE-2023-54171 tracing: Fix memory leak of iter->temp when reading trace_pipe

In the Linux kernel, the following vulnerability has been resolved: tracing: Fix memory leak of iter-temp when reading tracepipe kmemleak reports: unreferenced object 0xffff88814d14e200 size 256: comm "cat", pid 336, jiffies 4294871818 age 779.490s hex dump first 32 bytes: 04 00 01 03 00 00 00 00...