text segment corruption - probable suspects?

text segment corruption - probable suspects?

[Boyan Vladinov]

Hey guys,

recently I experience .text segment corruption in Kernel space. Could someone give some hints which can be the reason 
for this text segment corruption, because as we know it is read-only?

Thanks,
nayobix

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text segment corruption - probable suspects?

[Mulyadi Santosa]

On Tue, Jan 7, 2014 at 10:09 PM, Boyan Vladinov <nayobix@nayobix.org> wrote:
> Hey guys,
>
> recently I experience .text segment corruption in Kernel space. Could
> someone give some hints which can be the reason
> for this text segment corruption, because as we know it is read-only?

Could you share what evidence did you get so you can get conclusion
there happen such corruption?

IMHO, I suspect it is due RAM error...so it's not corruption coming
from kernel image itself

-- 
regards,

Mulyadi Santosa
Freelance Linux trainer and consultant

blog: the-hydra.blogspot.com
training: mulyaditraining.blogspot.com

text segment corruption - probable suspects?

[nayobix at nayobix.org]

On 01/23/2014 02:04 PM, Mulyadi Santosa wrote:
> On Tue, Jan 7, 2014 at 10:09 PM, Boyan Vladinov <nayobix@nayobix.org> wrote:
>> Hey guys,
>>
>> recently I experience .text segment corruption in Kernel space. Could
>> someone give some hints which can be the reason
>> for this text segment corruption, because as we know it is read-only?
> Could you share what evidence did you get so you can get conclusion
> there happen such corruption?
>
> IMHO, I suspect it is due RAM error...so it's not corruption coming
> from kernel image itself
>
I compared the addresses/instructions from the crash with these in 
vmlinux image and they were different in 1 or 2 bits. Yep, we also 
suspect RAM issues, but is it possible to be something other like DMA 
transfers?

text segment corruption - probable suspects?

[Greg Freemyer]

"nayobix at nayobix.org" <nayobix@nayobix.org> wrote:

>On 01/23/2014 02:04 PM, Mulyadi Santosa wrote:
>> On Tue, Jan 7, 2014 at 10:09 PM, Boyan Vladinov <nayobix@nayobix.org>
>wrote:
>>> Hey guys,
>>>
>>> recently I experience .text segment corruption in Kernel space.
>Could
>>> someone give some hints which can be the reason
>>> for this text segment corruption, because as we know it is
>read-only?
>> Could you share what evidence did you get so you can get conclusion
>> there happen such corruption?
>>
>> IMHO, I suspect it is due RAM error...so it's not corruption coming
>> from kernel image itself
>>
>I compared the addresses/instructions from the crash with these in 
>vmlinux image and they were different in 1 or 2 bits. Yep, we also 
>suspect RAM issues, but is it possible to be something other like DMA 
>transfers?

Lots of hardware issues cause bit flips.  I've seen it be ram, cpu cache, motherboard, disk controller, disk cables, power supply.  I'm sure they are other culprits (or more specific culprits).

Start with a ram test just because it is easy and a failure of memtest is pretty definitive about it being bad ram.  Even then it could be the power supply or a motherboard issue. 

Otherwise, I find using md5sum to hash a large file, then copying it and rehashing will trigger a failure in many cases.  If so, swap out parts until the problem goes away.  My personal number 1 failure is data cables.  They may get you the right data 99.9999% of the time, but that won't even let you reliably copy a 1 gb file.

I find new memory is often bad, but I rarely get failures after the DOA chips are replaced.

Greg
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