How Can MALLOC_CHECK_ and gdb Help Diagnose C Double Free or Corruption Errors?

Finding the Cause of Double Free or Corruption Errors

When a C program malfunctions with a "double free or corruption" error, identifying the underlying issue can be challenging. This article delves into how to utilize glibc's tools to pinpoint the source of this error.

Exploiting MALLOC_CHECK_ for Error Tolerance

Glibc, the GNU C library, provides a solution by enabling an error-tolerant version of malloc. Setting the MALLOC_CHECK_ environment variable to 2 initiates this behavior. Consequently, the program will terminate at the exact location where the double free occurs, making it easier to trace the error.

Integrating MALLOC_CHECK_ with gdb

gdb, a powerful debugger, integrates seamlessly with MALLOC_CHECK_. By executing the "set environment MALLOC_CHECK_ 2" command within gdb, you can activate the error-tolerant malloc behavior. Subsequently, running the program in gdb will cause it to crash at the point of the double free, displaying the problematic free() call within the backtrace.

Unveiling the Error's Origin

With the free() call identified, examining the call stack will often reveal the code path that led to the double free. This information empowers you to pinpoint the source of the error and implement corrective measures to prevent it from recurring.

Additional Resources

For further guidance on double free errors and MALLOC_CHECK_, consult the man page for malloc().

The above is the detailed content of How Can MALLOC_CHECK_ and gdb Help Diagnose C Double Free or Corruption Errors?. For more information, please follow other related articles on the PHP Chinese website!