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Date:   Sat, 21 Mar 2020 15:41:28 +0100
From:   Jan Psota <jasiu@belsznica.pl>
To:     linux-nfs@vger.kernel.org
Cc:     "Jason A. Donenfeld" <Jason@zx2c4.com>
Subject: Re: refcount underflow in nfsd41_destroy_cb
Message-ID: <20200321154128.58eb8ef2.jasiu@belsznica.pl>
In-Reply-To: <CAHmME9ro8BPBTMfu8dEbGmkH7qHLdQ=CXGEOW2C7MR4bmT6T+w@mail.gmail.com>
References: <CAHmME9ro8BPBTMfu8dEbGmkH7qHLdQ=CXGEOW2C7MR4bmT6T+w@mail.gmail.com>
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Hi! Previous and first trace for problem that Jason forwarded to you.

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Mar 19 11:08:07 agro kernel: ------------[ cut here ]------------
Mar 19 11:08:07 agro kernel: refcount_t: underflow; use-after-free.
Mar 19 11:08:07 agro kernel: WARNING: CPU: 0 PID: 15539 at lib/refcount.c:28 refcount_warn_saturate+
0xd9/0xe0
Mar 19 11:08:07 agro kernel: Modules linked in: udp_diag inet_diag wireguard curve25519_x86_64 libcurve25519_generic libchacha20poly1305 chacha_x86_64 libchacha poly1305_x86_64 ip6_udp_tunnel udp_tunnel libblake2s blake2s_x86_64 libblake2s_generic md5 xt_mac xt_nat xt_MASQUERADE xt_REDIRECT xt_owner xt_comment ipt_REJECT nf_reject_ipv4 xt_mark xt_hashlimit iptable_raw xt_multiport nfnetlink_log xt_NFLOG nf_log_ipv4 nf_log_common xt_LOG nf_nat_tftp nf_nat_sip nf_nat_h323 nf_nat_ftp nf_conntrack_tftp nf_conntrack_sip nf_conntrack_netlink nfnetlink nf_conntrack_h323 nf_conntrack_ftp nfsd auth_rpcgss nfs_acl lockd grace sunrpc cpufreq_ondemand msr bridge stp llc xt_tcpudp xt_conntrack iptable_mangle iptable_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 iptable_filter ip_tables x_tables btrfs blake2b_generic xor raid6_pq libcrc32c zstd_compress zstd_decompress zlib_deflate zlib_inflate hid_generic usbhid hid uas usb_storage snd_hda_codec_realtek snd_hda_codec_generic snd_hda_intel
  matroxfb_base
Mar 19 11:08:07 agro kernel:  snd_intel_dspcfg r8169 matroxfb_g450 matroxfb_Ti3026 matroxfb_accel e1000e cfbfillrect realtek snd_hda_codec libphy cfbimgblt cfbcopyarea matroxfb_DAC1064 g450_pll matroxfb_misc fb snd_hda_core atlantic mxm_wmi input_leds snd_hwdep xhci_pci pcspkr k10temp ptp xhci_hcd fbdev snd_pcm pps_core snd_timer snd wmi ohci_pci ohci_hcd i2c_piix4 ehci_pci ehci_hcd soundcore i2c_core acpi_cpufreq vhci_hcd usbip_core usbcore usb_common vhost_net vhost kvm_amd kvm irqbypass loop tun fuse it87 hwmon_vid hwmon
Mar 19 11:08:07 agro kernel: CPU: 0 PID: 15539 Comm: kworker/u16:1 Not tainted 5.6.0-rc6 #1
Mar 19 11:08:07 agro kernel: Hardware name: Gigabyte Technology Co., Ltd. GA-990FXA-UD5/GA-990FXA-UD5, BIOS F12 10/03/2013
Mar 19 11:08:07 agro kernel: Workqueue: rpciod rpc_async_schedule [sunrpc]
Mar 19 11:08:07 agro kernel: RIP: 0010:refcount_warn_saturate+0xd9/0xe0
Mar 19 11:08:07 agro kernel: Code: ff 48 c7 c7 e8 ff d5 81 c6 05 cd 49 b5 00 01 e8 4d 04 cf ff 0f 0b c3 48 c7 c7 90 ff d5 81 c6 05 b9 49 b5 00 01 e8 37 04 cf ff <0f> 0b c3 0f 1f 40 00 8b 07 3d 00 00 00 c0 74 12 83 f8 01 74 46 8d
Mar 19 11:08:07 agro kernel: RSP: 0018:ffffc9000056fde0 EFLAGS: 00010282
Mar 19 11:08:07 agro kernel: RAX: 0000000000000026 RBX: 0000000000000e81 RCX: 0000000000000007
Mar 19 11:08:07 agro kernel: RDX: 0000000000000007 RSI: 0000000000000092 RDI: ffff88881fc187c0
Mar 19 11:08:07 agro kernel: RBP: ffff8887f0394c70 R08: 00000000000015b7 R09: 0000000000000001
Mar 19 11:08:07 agro kernel: R10: 0000000000000000 R11: 0000000000000001 R12: ffff8885fec40510
Mar 19 11:08:07 agro kernel: R13: ffff888231700430 R14: 0000000000000001 R15: ffff888016454a80
Mar 19 11:08:07 agro kernel: FS:  0000000000000000(0000) GS:ffff88881fc00000(0000) knlGS:0000000000000000
Mar 19 11:08:07 agro kernel: CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
Mar 19 11:08:07 agro kernel: CR2: 000000000319e728 CR3: 0000000611f86000 CR4: 00000000000006f0
Mar 19 11:08:07 agro kernel: Call Trace:
Mar 19 11:08:07 agro kernel:  nfsd41_destroy_cb+0x36/0x50 [nfsd]
Mar 19 11:08:07 agro kernel:  rpc_free_task+0x3c/0x70 [sunrpc]
Mar 19 11:08:07 agro kernel:  __rpc_execute+0x3a5/0x3c0 [sunrpc]
Mar 19 11:08:07 agro kernel:  ? finish_task_switch+0x7f/0x250
Mar 19 11:08:07 agro kernel:  rpc_async_schedule+0x2f/0x50 [sunrpc]
Mar 19 11:08:07 agro kernel:  process_one_work+0x1ca/0x3c0
Mar 19 11:08:07 agro kernel:  worker_thread+0x45/0x3d0
Mar 19 11:08:07 agro kernel:  kthread+0xf3/0x130
Mar 19 11:08:07 agro kernel:  ? process_one_work+0x3c0/0x3c0
Mar 19 11:08:07 agro kernel:  ? kthread_park+0x80/0x80
Mar 19 11:08:07 agro kernel:  ret_from_fork+0x1f/0x30
Mar 19 11:08:07 agro kernel: ---[ end trace 175a0f52bbff4924 ]---

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