[Mingw-notify] [ mingw-Bugs-1813398 ] gdb running problem 0xfeeefeee

[SourceForge.net <no...@so...>]

Bugs item #1813398, was opened at 2007-10-15 06:51
Message generated for change (Comment added) made by infidel
You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=102435&aid=1813398&group_id=2435

Please note that this message will contain a full copy of the comment thread,
including the initial issue submission, for this request,
not just the latest update.
Category: gdb
Group: MinGW Web Site
>Status: Pending
>Resolution: Invalid
Priority: 5
Private: No
Submitted By: hola (minguser)
Assigned to: Nobody/Anonymous (nobody)
Summary: gdb running problem 0xfeeefeee

Initial Comment:
Working on my project I notice that the program run fine in general but if I try to run it on gdb I get a SIGSEGV.
I'm working on Xp platform using MinGW (MinGW gdb) and I've heard that Windows marks mem you freed with 0xfeeefeee and this is my problem with gdb. gdb marks a pointer with 0xfeeefeee and the programs crash (running in gdb). When I print the value running the pogram simply on "cmd" the value printed is different (like it should be). I made some test e notice that I really free a pointer Y but gdb seems to mark with 0xfeeefeee not just Y but either a pointer X that have an address bigger than Y. The memory for X is allocated immediately after the memory allocated for Y. 
More simply: I do this thing in my code.

___________________________________________
struct Lst {

    struct Lst *next;
     ....
};

struct Lst *list, *Y, **X, 

 list = calloc(1, sizeof(struct Lst));
 Y = list;

 list->next = calloc(1, sizeof(struct Lst)); 		
 X = &(list->next);
 ...
 
 free(Y);
 return *X;
// value of *X changes in gdb after free(Y)!!!
_____________________________________________



OS version: XP
gcc version:  3.2.3
ld version: GNU ld version 2.13.90 20030111
mingw version: MinGW-3.0.0-1.exe
build environment: cmd

I make a small test file too...





----------------------------------------------------------------------

>Comment By: Luke Dunstan (infidel)
Date: 2007-10-15 21:11

Message:
Logged In: YES 
user_id=30442
Originator: NO

Your code is incorrect. X is pointing to memory that has been freed by
"free(Y)", so you cannot access this memory.


----------------------------------------------------------------------

You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=102435&aid=1813398&group_id=2435