Kernel panic in SMB2_sess_setup() after a CIFS filesystem got disconnected

This document (7023105) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server 12 Service Pack 2 (SLES 12 SP2)
SUSE Linux Enterprise Server 12 Service Pack 3 (SLES 12 SP3)

Situation

A kernel panic may happen if a CIFS filesystem is disconnected as the SMB server got rebooted.

A typical stack trace of the failing task looks like:

PID: 6705   TASK: ffff88003680c8c0  CPU: 1   COMMAND: "kworker/1:0"
 #0 [ffff88012ad4f9c0] machine_kexec at ffffffff81058fdc
 #1 [ffff88012ad4fa10] __crash_kexec at ffffffff8111782a
 #2 [ffff88012ad4fad0] crash_kexec at ffffffff811178fc
 #3 [ffff88012ad4fae0] oops_end at ffffffff8101a604
 #4 [ffff88012ad4fb00] no_context at ffffffff81066e77
 #5 [ffff88012ad4fb50] __do_page_fault at ffffffff81067975
 #6 [ffff88012ad4fbb8] do_page_fault at ffffffff81067dcb
 #7 [ffff88012ad4fbe0] page_fault at ffffffff81619402
    [exception RIP: SMB2_sess_setup+0x3a8]
    RIP: ffffffffa04b4a88  RSP: ffff88012ad4fc98  RFLAGS: 00010296
    RAX: 000000000000005b  RBX: ffff8800af1ea000  RCX: ffffea0002d4a620
    RDX: 000000000000005c  RSI: ffff8800b5d62ac0  RDI: 0000000000000000
    RBP: ffff88012ad4fd40   R8: 0000000000000000   R9: 000001c90d5987d6
    R10: 000001c90d5987d6  R11: 0000000000000000  R12: 0000000000000000
    R13: 00000000fffffff5  R14: ffff8800af3d6800  R15: 0000000000000001
    ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
 #8 [ffff88012ad4fd48] cifs_setup_session at ffffffffa0487c8d [cifs]
 #9 [ffff88012ad4fd70] smb2_reconnect at ffffffffa04b3e0c [cifs]
#10 [ffff88012ad4fde8] smb2_reconnect_server at ffffffffa04b6b40 [cifs]
#11 [ffff88012ad4fe38] process_one_work at ffffffff810989e4
#12 [ffff88012ad4fe78] worker_thread at ffffffff810995c6
#13 [ffff88012ad4fed0] kthread at ffffffff8109ead9
#14 [ffff88012ad4ff50] ret_from_fork at ffffffff81616505

Resolution

A patch has been issued for the bug in the cifs module.

If the latest kernel cannot be installed, please install one of the kernels listed below (or newer) to apply the patch.

SLES12 SP2 LTSS: 4.4.121-92.92.1

SLES12 SP3: 4.4.143-94.47.1

Cause

Additional Information

Disclaimer

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