linux-kernel - NULL pointer dereference in ext4_superblock_csum

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Date:	Wed, 26 Jun 2013 18:53:31 +0200
From:	Michael Gissing <mgissing@....tugraz.at>
To:	linux-kernel@...r.kernel.org
Subject: NULL pointer dereference in ext4_superblock_csum_set

Hi,

tl,dr; I have a sd card which I suspect to have a corrupted fs. When I 
insert the card into my laptop's reader, I get the following:

BUG: unable to handle kernel NULL pointer dereference at (null)
IP: [<ffffffff8123bb0d>] ext4_superblock_csum_set+0x4d/0xd0

Long story: It seems like i got a corrupted SD card when running one of 
my Raspberry pis in turbo mode. I wanted to check the card on my laptop, 
I got a kernel error. (please find it in the attached .txt)

The installed system is Linux Mint 14 Nadia (the one based on Ubuntu 12.10)

uname -a:
Linux x200t 3.5.0-34-generic #55-Ubuntu SMP Thu Jun 6 20:18:19 UTC 2013 
x86_64 x86_64 x86_64 GNU/Linux

Cinnamon gives me a popup too:

Error mounting /dev/sdb2 at 
/media/michael/41cd5baa-7a62-4706-b8e8-02c43ccee8d9: Command-line `mount 
-t "ext4" -o "uhelper=udisks2,nodev,nosuid" "/dev/sdb2" 
"/media/michael/41cd5baa-7a62-4706-b8e8-02c43ccee8d9"' was signaled with 
signal SIGKILL (9):

I couldn't reproduce the error, something must have changed the sd card. 
I've created a dd image of the card, but I did it after the error 
occured. I haven't tried whether the image causes the error yet, I need 
the card at the moment.

Is this something you want to look into? If so, let me know, I'll try to 
help.

Please CC me as I'm not subscribed to the list.

Michael

View attachment "linux_kernel_null_pointer_ext4.txt" of type "text/plain" (6484 bytes)