Kernel panic with NULL pointer dereference in check_nfsd_access()

Solution Verified - Updated -

Issue

  • System crashes with following messages in the kernel ring buffer :
[22237.710797] BUG: unable to handle kernel NULL pointer dereference at 0000000000000078
[22237.712898] IP: [<ffffffffc07c2bf6>] check_nfsd_access+0x6/0x80 [nfsd]
[22237.714875] PGD 0
[22237.716795] Oops: 0000 [#1] SMP
[22237.718685] Modules linked in: nfsv3 rpcsec_gss_krb5 nfsv4 dns_resolver nfs fscache ext4 mbcache jbd2 loop sb_edac edac_core intel_powerclamp coretemp intel_rapl iosf_mbi kvm_intel kvm irqbypass crc32_pclmul ghash_clmulni_intel [..]
[22237.732282] CPU: 3 PID: 7566 Comm: nfsd Tainted: G        W      ------------   3.10.0-665.el7.x86_64 #1
[22237.734208] Hardware name: Dell Inc. PowerEdge R430/03XKDV, BIOS 1.1.10 03/10/2015
[22237.736115] task: ffff8a0c7b368000 ti: ffff8a0ccbedc000 task.ti: ffff8a0ccbedc000
[22237.738001] RIP: 0010:[<ffffffffc07c2bf6>]  [<ffffffffc07c2bf6>] check_nfsd_access+0x6/0x80 [nfsd]
[22237.739925] RSP: 0018:ffff8a0ccbedfd88  EFLAGS: 00010246
[22237.741841] RAX: 0000000000000570 RBX: ffff8a0cd5ea6000 RCX: ffff8a0cdab28000
[22237.743709] RDX: 0000000000000004 RSI: ffff8a0cbeae2000 RDI: 0000000000000000
[22237.745544] RBP: ffff8a0ccbedfdd8 R08: 0000000000019bc0 R09: ffffffffc07dd25e
[22237.747355] R10: ffff8a0cdd2d9bc0 R11: ffff8a0cdab28080 R12: ffff8a0cbeae2000
[22237.749138] R13: ffff8a0cd5ea6068 R14: ffff8a0cd5ea61a8 R15: ffff8a0cdab28000
[22237.750891] FS:  0000000000000000(0000) GS:ffff8a0cdd2c0000(0000) knlGS:0000000000000000
[22237.752665] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[22237.754427] CR2: 0000000000000078 CR3: 00000003f9fea000 CR4: 00000000001407e0
[22237.756174] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[22237.757887] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[22237.759558] Stack:
[22237.761189]  ffff8a0ccbedfdd8 ffffffffc07cd9dd ffff8a0cdab28080 00000000000009f0
[22237.762828]  ffff8a0cdab28080 ffff8a0cbeae2000 ffffffffc07f8138 ffff8a0b386b2018
[22237.764442]  ffff8a0b386b2000 000000000000001c ffff8a0ccbedfe10 ffffffffc07b8593
[22237.766029] Call Trace:
[22237.767584]  [<ffffffffc07cd9dd>] ? nfsd4_proc_compound+0x56d/0x790 [nfsd]
[22237.769138]  [<ffffffffc07b8593>] nfsd_dispatch+0xd3/0x280 [nfsd]
[22237.770689]  [<ffffffffc0774453>] svc_process_common+0x453/0x6f0 [sunrpc]
[22237.772211]  [<ffffffffc07747f3>] svc_process+0x103/0x190 [sunrpc]
[22237.773694]  [<ffffffffc07b7eff>] nfsd+0xdf/0x150 [nfsd]
[22237.775143]  [<ffffffffc07b7e20>] ? nfsd_destroy+0x80/0x80 [nfsd]
[22237.776557]  [<ffffffffaf6b093f>] kthread+0xcf/0xe0
[22237.777946]  [<ffffffffaf6b0870>] ? insert_kthread_work+0x40/0x40
[22237.779308]  [<ffffffffafcb0d18>] ret_from_fork+0x58/0x90
[22237.780643]  [<ffffffffaf6b0870>] ? insert_kthread_work+0x40/0x40
[22237.781948] Code: 03 00 00 4c 89 ea e8 dc 70 4d ef 4c 8b ad 88 fe ff ff e9 bb fd ff ff 0f 1f 40 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 55 <44> 8b 47 78 48 89 e5 44 89 c0 48 8d 54 c7 7c 48 8b 86 d8 1a 00
[22237.784635] RIP  [<ffffffffc07c2bf6>] check_nfsd_access+0x6/0x80 [nfsd]
[22237.785920]  RSP <ffff8a0ccbedfd88>
[22237.787162] CR2: 0000000000000078

Environment

  • Red Hat Enterprise Linux 7
  • NFS

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