If you run this program multiple times through GDB, you will see that: Notice the handy comments automatically added by objdump’s artificial intelligence module. Minimal reproduction example with disassembly analysisĤ005d6: 66 2e 0f 1f 84 00 00 nopw %cs:0x0(%rax,%rax,1) Valgrind doesn’t work well with stack-related errors, but like a debugger, it may help you pin-point the location and reason for the crash. You can get some information about the point of overflow by running the program with a debugger. ![]() Note that -fstack-protector should always be turned on for release builds as it is a security feature. In that case you will get a different error, most likely a segmentation fault as you are trying to access an illegal memory location. To get some insight, you can try disabling this protection of gcc using option -fno-stack-protector while compiling. An input string of size greater than 10 causes corruption of this variable resulting in SIGABRT to terminate the program. ![]() ![]() The compiler, (in this case gcc) adds protection variables (called canaries) which have known values. Stack Smashing here is actually caused due to a protection mechanism used by gcc to detect buffer overflow errors.
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