Re: malloc and free

[Eric Bambach <eric@cisu.net>]

On Friday 24 December 2004 12:39 pm, you wrote:
> hi
>
> routine xyz uses malloc and free functions. it gives
> accurate and correct result if called once.
>
> but if the function is called in a loop N number of
> times then probably it gives segmentation fault.
>
> what is the reason?  can any body guess or test code
> is needed?
>
> thanks
>
> ankit jain

A common cause of failure in the malloc/free routines is memory corruption. 
The trick about memory corruption and buffer overflows is that they work 
sometimes/most of the time. Perhaps you are doing out-of-bounds reading or 
(gak!) writing with the memory. Try running it under valgrind to see if this 
is the case.

Also, although routine xyz may not corrupt the memory perhaps something else 
in your program is? Writing in strange places confuses libc and can result in 
a segfault in places that can be quite far away from the original spot of 
corruption.

----------------------------------------
--EB

> All is fine except that I can reliably "oops" it simply by trying to read
> from /proc/apm (e.g. cat /proc/apm).
> oops output and ksymoops-2.3.4 output is attached.
> Is there anything else I can contribute?

The latitude and longtitude of the bios writers current position, and
a ballistic missile.

                --Alan Cox LKML-December 08,2000 

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