Re: [Unionfs] NULL pointer dereference if copyup_dentry() failed?

From: Tomas M <tomas@slax.org>
To: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: ezk@cs.sunysb.edu, unionfs@fsl.cs.sunysb.edu,
	linux-fsdevel@vger.kernel.org
Subject: Re: [Unionfs] NULL pointer dereference if copyup_dentry() failed?
Date: Sun, 21 Sep 2008 10:47:44 +0200	[thread overview]
Message-ID: <48D60A30.4060404@slax.org> (raw)
In-Reply-To: <200809211616.CHH52682.HSJFOFtOLFVQOM@I-love.SAKURA.ne.jp>

> BUG: unable to handle kernel NULL pointer dereference at 00000072

I keep seeing this error for many years with unionfs.
Would anybody please explain what this error means?
and what does it say about the code?

Thank you very much

Tomas M

Tetsuo Handa wrote:
> Hello.
> 
> I tried 2.6.27-rc6 + unionfs 2.5 , but this problem is remaining.
> 
> Regards.
> 
> ----- CentOS 5.2 ( gcc version 4.1.2 ) -----
> TOMOYO-ERROR: sys_chmod() denied for /bin/touch
> BUG: unable to handle kernel NULL pointer dereference at 00000072
> IP: [<c048d5ac>] notify_change+0x1c/0x1d8
> *pde = 00000000 
> Oops: 0000 [#1] SMP DEBUG_PAGEALLOC
> Modules linked in: ipv6 sbs sbshc battery backlight lp floppy ide_cd_mod cdrom serio_raw ac parport_pc parport rtc_cmos rtc_core button rtc_lib pcnet32 mii pcspkr unionfs mptspi scsi_transport_spi mptscsih mptbase sd_mod scsi_mod ext3 jbd [last unloaded: microcode]
> 
> Pid: 2291, comm: touch Not tainted (2.6.27-rc6-unionfs #2)
> EIP: 0060:[<c048d5ac>] EFLAGS: 00010246 CPU: 0
> EIP is at notify_change+0x1c/0x1d8
> EAX: 00000000 EBX: 00000070 ECX: 00000000 EDX: dec00f14
> ESI: dec00f14 EDI: d4b20df4 EBP: dec00ea4 ESP: dec00e7c
>  DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068
> Process touch (pid: 2291, ti=dec00000 task=db6a20e0 task.ti=dec00000)
> Stack: d4bbee20 d4b20ec0 00000000 22222222 22222222 22222222 22222222 d4b20e88 
>        dec00f14 d4b20df4 dec00ed8 e08b5af6 dec00f14 d4bbe2a0 d4bbee20 d4bc02a0 
>        d4bcadf4 00000000 d4bcadb0 00000000 00000000 dec00f14 00000000 dec00f08 
> Call Trace:
>  [<e08b5af6>] ? unionfs_setattr+0x29c/0x3b4 [unionfs]
>  [<c048d742>] ? notify_change+0x1b2/0x1d8
>  [<c0497a10>] ? utimes_common+0x100/0x13a
>  [<c0497aef>] ? do_utimes+0xa5/0xbf
>  [<c0497b73>] ? sys_futimesat+0x6a/0x78
>  [<c0453968>] ? audit_syscall_entry+0x101/0x12b
>  [<c05ee02a>] ? do_page_fault+0x0/0x58d
>  [<c0497b91>] ? sys_utimes+0x10/0x12
>  [<c04038b1>] ? sysenter_do_call+0x12/0x31
>  =======================
> Code: e8 11 7f 00 00 31 c0 83 c4 14 5b 5e 5f 5d c3 55 89 e5 57 56 89 d6 53 83 ec 1c 8b 1e 89 45 d8 8b 40 28 f7 c3 07 00 01 00 89 45 e0 <66> 8b 50 72 66 89 55 e4 74 10 83 cf ff f6 80 f0 01 00 00 0c 0f 
> EIP: [<c048d5ac>] notify_change+0x1c/0x1d8 SS:ESP 0068:dec00e7c
> ---[ end trace 403e02e983cf15ec ]---
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