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Valgrind Dynamic Instrumentation Tool: Detect Memory Errors Easily

Valgrind is an open-source dynamic instrumentation tool developed by Julian Seward at Cambridge University, UK. It helps find memory errors such as invalid accesses and leaks, popular in software testing. Easily identify errors like invalid memory access or unfreed memory.

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Valgrind Dynamic Instrumentation Tool: Detect Memory Errors Easily

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  1. Dynamic Instrumentation - Valgrind • Developed by Julian Seward at/around Cambridge University,UK • Google-O'Reilly Open Source Award for "Best Toolmaker" 2006 • A merit (bronze) Open Source Award 2004 • Open source • works on x86, AMD64, PPC code • Easy to execute, e.g.: • valgrind --tool=memcheck ls • It becomes very popular • One of the two most popular dynamic instrumentation tools • Pin and Valgrind • Very good usability, extendibility, robust • 25MLOC • Mozilla, MIT, CMU-security, Purdue and many other places • Overhead is the problem • 5-10X slowdown without any instrumentation

  2. Valgrind debugging tool • Goal: detect memory errors • Accesses outside of memory bounds • Memory leaks • Great for finding errors that would only show during harsh test cases

  3. Valgrind: Example Errors • Can you find twoerrors in this program? #include <stdlib.h> void f(void) { int* x = malloc(10 * sizeof(int)); x[10] = 0; } int main(void) { f(); return 0; } 1. Invalid memory access 2. Memory never free()’d

  4. Running Example in Valgrind • Running valgrind with the program: • valgrind --leak-check=yes myprog arg1 arg2 • Invalid access output (error 1): • Memory leak output (error 2): ==19182== Invalid write of size 4 ==19182== at 0x804838F: f (example.c:6) ==19182== by 0x80483AB: main (example.c:11) Where the error occurs Process ID ==19182== 40 bytes in 1 blocks are definitely lost in loss record 1 of 1 ==19182== at 0x1B8FF5CD: malloc (vg_replace_malloc.c:130) ==19182== by 0x8048385: f (a.c:5) ==19182== by 0x80483AB: main (a.c:11) Size of the leak

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