poc: uid=65534 euid=65534 test=2
T2 step1: NORMAL read(65536) = 65536
T2 attempt   1: errno=14 nz[0,512)=0 nz[512,end)=0 first_nz=0xffffffffffffffff kptr=0
T2 RESULT: LEAK/UNDERFLOW at attempt 1 (errno=14, 0 bytes beyond the 512-byte request, 0 kernel-pointer qwords)
T2 leak sample: /tmp/dfp_leak_1376.bin
T2 mapping head (stale first chunk) @0x800a00000:
  0000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
  0010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
  0020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
  0030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
  0040: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
  0050: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00