Re: Dereferenced null pointer

[David Gillies <daggillies@xxxxxxxxx>]

The usual result will be instant and spectacular
failure (the kernel hanging is unlikely). Your kernel
will oops, and you will see something like the
following:

Unable to handle kernel NULL pointer dereference at
virtual address 00000000
printing eip:
c48370c3 
*pde = 00000000
Oops: 0002
CPU: 0
EIP: 0010:[<c48370c3>]
EFLAGS: 00010286
eax: ffffffea ebx: c2281a20 ecx: c48370c0 edx:
c2281a40
esi: 4000c000 edi: 4000c000 ebp: c38adf8c esp:
c38adf8c ds: 0018 es: 0018 ss: 0018
Process ls (pid: 23171, stackpage=c38ad000)
Stack: 0000010e c01356e6 c2281a20 4000c000 0000010e
...
...
...
[from Rubini and Corbet]

and you will most certainly have to reboot the
machine. Whether anything worse happens is
indeterminable - if you're writing to a device and the
kernel throws its hands up then you run the risk of a
corrupt filesystem, for example. Don't develop
filesystem drivers on hardware containing data you
care about.

Best Wishes

David Gillies
San Jose
Costa Rica

--- Frank.A.Uepping@t-online.de wrote:
> What happens when a null pointer is dereferenced in
> the Linux kernel?
> How fatal is this to the running kernel/system?
> Is there need to reboot the kernel?
> 
> /FAU
> 
> 
> --
> Kernelnewbies: Help each other learn about the Linux
> kernel.
> Archive:      
> http://mail.nl.linux.org/kernelnewbies/
> FAQ:           http://kernelnewbies.org/faq/
> 


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