From: Zheng Liu <gnehzuil.liu@gmail.com>
Subject: Re: kernel BUG at fs/ext4/namei.c:2572!
Date: Fri, 19 Jul 2013 09:17:33 +0800
Message-ID: <20130719011733.GC21615@gmail.com>
References: <20130717161944.GA19405@redhat.com>
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To: Dave Jones <davej@redhat.com>,
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Hi Dave,

Thanks for reporting this.

On Wed, Jul 17, 2013 at 12:19:44PM -0400, Dave Jones wrote:
> Seen while fuzzing..
> 
> kernel BUG at fs/ext4/namei.c:2572!
> invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
> Modules linked in: dlci bridge stp hidp cmtp kernelcapi l2tp_ppp l2tp_netlink l2tp_core sctp libcrc32c rfcomm tun fuse nfnetli
> nk can_raw ipt_ULOG can_bcm x25 scsi_transport_iscsi ipx p8023 p8022 appletalk phonet psnap vmw_vsock_vmci_transport af_key vmw_vmci rose vsock atm can netrom ax25 af_rxrpc ir
> da pppoe pppox ppp_generic slhc bluetooth nfc rfkill rds caif_socket caif crc_ccitt af_802154 llc2 llc snd_hda_codec_realtek snd_hda_intel snd_hda_codec serio_raw snd_pcm pcsp
> kr edac_core snd_page_alloc snd_timer snd soundcore r8169 mii sr_mod cdrom pata_atiixp radeon backlight drm_kms_helper ttm
> CPU: 1 PID: 1812571 Comm: trinity-child2 Not tainted 3.11.0-rc1+ #12
> Hardware name: Gigabyte Technology Co., Ltd. GA-MA78GM-S2H/GA-MA78GM-S2H, BIOS F12a 04/23/2010
> task: ffff88007dfe69a0 ti: ffff88010f7b6000 task.ti: ffff88010f7b6000
> RIP: 0010:[<ffffffff8125ce69>]  [<ffffffff8125ce69>] ext4_orphan_add+0x299/0x2b0
> RSP: 0018:ffff88010f7b7cf8  EFLAGS: 00010202
> RAX: 0000000000000000 RBX: ffff8800966d3020 RCX: 0000000000000000
> RDX: 0000000000000000 RSI: ffff88007dfe70b8 RDI: 0000000000000001
> RBP: ffff88010f7b7d40 R08: ffff880126a3c4e0 R09: ffff88010f7b7ca0
> R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801271fd668
> R13: ffff8800966d2f78 R14: ffff88011d7089f0 R15: ffff88007dfe69a0
> FS:  00007f70441a3740(0000) GS:ffff88012a800000(0000) knlGS:00000000f77c96c0
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000002834000 CR3: 0000000107964000 CR4: 00000000000007e0
> DR0: 0000000000780000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
> Stack:
>  0000000000002000 00000020810b6dde 0000000000000000 ffff88011d46db00
>  ffff8800966d3020 ffff88011d7089f0 ffff88009c7f4c10 ffff88010f7b7f2c
>  ffff88007dfe69a0 ffff88010f7b7da8 ffffffff8125cfac ffff880100000004
> Call Trace:
>  [<ffffffff8125cfac>] ext4_tmpfile+0x12c/0x180
>  [<ffffffff811cba78>] path_openat+0x238/0x700
>  [<ffffffff8100afc4>] ? native_sched_clock+0x24/0x80
>  [<ffffffff811cc647>] do_filp_open+0x47/0xa0
>  [<ffffffff811db73f>] ? __alloc_fd+0xaf/0x200
>  [<ffffffff811ba2e4>] do_sys_open+0x124/0x210
>  [<ffffffff81010725>] ? syscall_trace_enter+0x25/0x290
>  [<ffffffff811ba3ee>] SyS_open+0x1e/0x20
>  [<ffffffff816ca8d4>] tracesys+0xdd/0xe2
>  [<ffffffff81001001>] ? start_thread_common.constprop.6+0x1/0xa0
> Code: 04 00 00 00 89 04 24 31 c0 e8 c4 77 04 00 e9 43 fe ff ff 66 25 00 d0 66 3d 00 80 0f 84 0e fe ff ff 83 7b 48 00 0f 84 04 fe ff ff <0f> 0b 49 8b 8c 24 50 07 00 00 e9 88 fe ff ff 0f 1f 84 00 00 00 
> 
> 
> 2571         J_ASSERT((S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
> 2572                   S_ISLNK(inode->i_mode)) || inode->i_nlink == 0);

I guess that is because we need to call drop_nlink to let ->i_nlink == 0
before adding this inode into orphan list in ext4_tmpfile().  I will try
to fix it later.

Regards,
                                                - Zheng

> 
> 
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