[asterisk-dev] [Code Review] MALLOC_DEBUG enhancements.

[David Lee]

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/branches/1.8/main/astmm.c
<https://reviewboard.asterisk.org/r/2182/#comment14153>

    If reg-> len isn't a multiple of sizeof(unsigned int), won't this overwrite the allocated memory by a few bytes? For region size 1, on 64 bit, it will allocate 141 bytes, but this writes 144.


- David


On Nov. 6, 2012, 4:54 p.m., rmudgett wrote:
> 
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> (Updated Nov. 6, 2012, 4:54 p.m.)
> 
> 
> Review request for Asterisk Developers.
> 
> 
> Summary
> -------
> 
> MALLOC_DEBUG enhancements.
> 
> * Makes malloc() behave like calloc().  It will return a memory block
> filled with 0x55.  A nonzero value.
> 
> * Makes free() fill the released memory block and boundary fence's with
> 0xdeaddead.  Any pointer use after free is going to have a pointer
> pointing to 0xdeaddead.  The 0xdeaddead pointer is usually an invalid
> memory address so a crash is expected.
> 
> * Puts the freed memory block into a circular array so it is not reused
> immediately.
> 
> * When the circular array rotates out a memory block to the heap it checks
> that the memory has not been altered from 0xdeaddead.
> 
> * Made the astmm_log message wording better.
> 
> * Made crash if the DO_CRASH menuselect option is enabled and something is
> found.
> 
> 
> Diffs
> -----
> 
>   /branches/1.8/include/asterisk/astmm.h 375992 
>   /branches/1.8/include/asterisk/utils.h 375992 
>   /branches/1.8/main/asterisk.c 375992 
>   /branches/1.8/main/astmm.c 375992 
>   /branches/1.8/main/utils.c 375992 
> 
> Diff: https://reviewboard.asterisk.org/r/2182/diff
> 
> 
> Testing
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> 
> The MALLOC_DEBUG enhancements were instrumental in pointing out a memory corruption problem.
> 
> 
> Thanks,
> 
> rmudgett
> 
>

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