What causes a SIGSEGV

Question

I need to know the root cause of the segmentation fault (SIGSEGV), and how to handle it.

Answer 1

Here is an example of SIGSEGV.

root@pierr-desktop:/opt/playGround# cat test.c
int main()
{
     int * p ;
     * p = 0x1234;
     return 0 ;
}
root@pierr-desktop:/opt/playGround# g++ -o test test.c  
root@pierr-desktop:/opt/playGround# ./test 
Segmentation fault

And here is the detail.

How to handle it?

1. Avoid it as much as possible in the first place.

   Program defensively: use assert(), check for NULL pointer , check for buffer overflow.

   Use static analysis tools to examine your code.

   compile your code with -Werror -Wall.

   Has somebody review your code.

2. When that actually happened.

   Examine you code carefully.

   Check what you have changed since the last time you code run successfully without crash.

   Hopefully, gdb will give you a call stack so that you know where the crash happened.

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EDIT : sorry for a rush. It should be *p = 0x1234; instead of p = 0x1234;