Valgrind Tutorial - Part 5

-
Errors Occur Due to Invalid System Call Parameter can be found using valgrind


int main(void)
{
        int *ptr;
        ptr = malloc(10);
        read(0, ptr, 100);        /* Error: unaddressable bytes */
        free(ptr);
        return 0;
}
You can see the following code we allocated 10 bytes and we are trying to read 100 bytes from stdin(standard input). Run the following commands gcc -o app app.c -g valgrind --tool=memcheck --leak-check=yes ./app

Comments

Post a Comment

Popular posts from this blog

bb.utils.contains yocto

-
Image
bb.utils.contains  is most commonly used function in Yocto. grep in poky directory returned with 696 count. $ grep -nr 'bb.utils.contains' poky/ | wc -l 696 It's definition is present in 'poky/bitbake/lib/bb/utils.py' file This function returns third argument if the second argument is subset of the first argument else returns fourth argument Let's take an example to understand this. You can see from the above screenshot, when the second argument is a subset of first argument, "present" was returned, else "notpresent" was returned We can also use bb.utils.contains inside if loop. This we can use inside a recipe. if ${@bb.utils.contains('SOMEFLAG','NEWVALUE3','true','false',d)}; then     FOO = 'HELLO' fi
Read more

make config vs oldconfig vs defconfig vs menuconfig vs savedefconfig

-
Image
Building the Linux Kernel is a two-step process: Configuring the Kernel options Building the Kernel with those options. There are many methods available for configuring the kernel. make config: Text-based Configuration.  Options are prompted one after another. All options need to be answered Access to former options is not possible make menuconfig: Menu-driven user interface Allows to navigate forwards and backward directly between features Allows to load and save files with filenames different from ".config" Provides search feature It uses ncurses library for GUI. If the ncurses library is not installed, make menuconfig option fails. To install ncurses library on Ubuntu: sudo apt-get install libncurses5-dev make defconfig: Creates a ".config" file with default options from the ARCH supplied defconfig Configurations are generally stored in the directory: arch/$(ARCH)/configs $ ls arch/x86/configs/ i386_defconfi...
Read more

vermagic in Linux Device Driver

-
Image
Vermagic is a magic string present in the Linux Kernel and added into the .modinfo section of the Linux Kernel Modules. This is used to verify whether the kernel module was compiled for the particular kernel version or not. ‘VERMAGIC_STRING’ is generated by the kernel configuration. #define VERMAGIC_STRING                         \     UTS_RELEASE " "                         \     MODULE_VERMAGIC_SMP MODULE_VERMAGIC_PREEMPT             \     MODULE_VERMAGIC_MODULE_UNLOAD MODULE_VERMAGIC_MODVERSIONS   \     MODULE_ARCH_VERMAGIC                        \     MODULE_RANDSTRUCT_PLUGIN Code: Output: If we change the value of 'vermagic' string using 'MODULE_INFO', we will get the error while lo...
Read more