Re: Value 0xd0d0d0d0 ?

2002-11-10 Thread M. Warner Losh 
In message: <[EMAIL PROTECTED]>
Aurelien Nephtali <[EMAIL PROTECTED]> writes:
: I would like to know where/when the value 0xd0d0d0d0 is assigned to a pointer ?
: Sometimes I have some pointers which have a correct value before and suddenly
: they got this odd 0xd0d0d0d0 value :/

That's a feature of FreeBSD's malloc.  On free, the old memory is
overwritten with 0xd0 to preclude access after free (which is
undefined and a source of many bugs).  This is a bug in your program
almost certainly.

man malloc will show you how to turn this off.

Warner

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Re: Value 0xd0d0d0d0 ?

2002-11-09 Thread Poul-Henning Kamp 
In message <[EMAIL PROTECTED]>, Aurelien Nephtali writes:
>
>--lrZ03NoBR/3+SXJZ
>Content-Type: text/plain; charset=iso-8859-15
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>
>Hi,
>
>I would like to know where/when the value 0xd0d0d0d0 is assigned to a point=
>er ?
>Sometimes I have some pointers which have a correct value before and sudden=
>ly
>they got this odd 0xd0d0d0d0 value :/

When you have mistakes in your malloc(3)/free(3) handling.

See the malloc(3) manual page.

Try using electric-fence from the ports collection.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
[EMAIL PROTECTED] | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.

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Re: Value 0xd0d0d0d0 ?

2002-11-09 Thread Steve Kargl 
On Sat, Nov 09, 2002 at 01:49:30PM +0100, Aurelien Nephtali wrote:
> Hi,
> 
> I would like to know where/when the value 0xd0d0d0d0 is assigned
> to a pointer ?
> Sometimes I have some pointers which have a correct value before
> and suddenly they got this odd 0xd0d0d0d0 value :/
> 

man 3 malloc

Read about the J option and see revision 1.51
of src/lib/libc/stdlib/malloc.c.

-- 
Steve

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Value 0xd0d0d0d0 ?

2002-11-09 Thread Aurelien Nephtali 
Hi,

I would like to know where/when the value 0xd0d0d0d0 is assigned to a pointer ?
Sometimes I have some pointers which have a correct value before and suddenly
they got this odd 0xd0d0d0d0 value :/

-- Aurélien



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