Linux SIGSEGV (Segmentation Violation)

SIGSEGV (Signal 11) indicates a segmentation fault where a program attempts to access memory it doesn't have permission to access, typically causing immediate termination.

Common Causes

Dereferencing a null or invalid pointer
Accessing memory beyond allocated bounds (buffer overflow)
Writing to read-only memory
Stack overflow or corruption
Using freed or uninitialized memory

How to Fix

1 Debug with GDB

Use GNU Debugger to get a backtrace and identify the exact line causing the fault.

BASH

 $ gdb ./your_program
run
# After crash:
bt
where

2 Enable Core Dumps

Configure system to generate core dump files for post-mortem analysis.

BASH

 $ ulimit -c unlimited
echo "/tmp/core.%e.%p" > /proc/sys/kernel/core_pattern

3 Use Address Sanitizer

Compile with ASAN to detect memory errors during runtime.

BASH

 $ gcc -fsanitize=address -g -o program program.c
./program

4 Check System Logs

Examine kernel logs for additional context about the segmentation fault.

BASH

 $ dmesg | tail -20
journalctl -xe | grep -i segfault