RHEL8、cifs: 解放された cifs_readdata 構造による smb2_readv_callback でのパニック

Issue

• RHEL8 はこのスタックでパニックになります。

PID: 3984     TASK: ffff9975e2880000  CPU: 6    COMMAND: "cifsd"
#0 [ffffaab1c8017940] machine_kexec at ffffffff97e6564e
#1 [ffffaab1c8017998] __crash_kexec at ffffffff97fa576d
#2 [ffffaab1c8017a60] panic at ffffffff97eed98b
#3 [ffffaab1c8017b00] no_context at ffffffff97e763bf
#4 [ffffaab1c8017b58] __bad_area_nosemaphore at ffffffff97e7671c
#5 [ffffaab1c8017ba0] do_page_fault at ffffffff97e76fb7
#6 [ffffaab1c8017bd0] page_fault at ffffffff9880111e
[exception RIP: smb2_readv_callback+81]
RIP: ffffffffc103d311  RSP: ffffaab1c8017c88  RFLAGS: 00010246
RAX: 0000000000000000  RBX: ffff9976a6edb300  RCX: dead000000000200
RDX: ffff99751859f000  RSI: ffff9976a6edb300  RDI: ffff9976a6edb300
RBP: ffff9979831228c8   R8: ffff9974221e8000   R9: 0000000000000000
R10: 0000000001539094  R11: 0000000000000001  R12: 0000000000000000
R13: ffff99751859f1c0  R14: 0000000000000000  R15: ffff9978a7a2b400
ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
#7 [ffffaab1c8017d10] cifs_reconnect at ffffffffc0fff27b [cifs]
#8 [ffffaab1c8017d90] cifs_readv_from_socket at ffffffffc0fffd5d [cifs]
#9 [ffffaab1c8017dc8] cifs_read_from_socket at ffffffffc0fffe5a [cifs]
#10 [ffffaab1c8017e48] cifs_demultiplex_thread at ffffffffc10001f6 [cifs]
#11 [ffffaab1c8017f10] kthread at ffffffff97f12b3a
#12 [ffffaab1c8017f50] ret_from_fork at ffffffff98800255