Attachment 243919 Details for Bug 272992 – dl_iterate_phdr-via-dlsym.c

dl_iterate_phdr-via-dlsym.c

dl_iterate_phdr-via-dlsym.c (text/plain), 1.25 KB, created by Yuri Victorovich on 2023-08-07 06:40:17 UTC

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Creator: Yuri Victorovich

Created: 2023-08-07 06:40:17 UTC

Size: 1.25 KB

patch

obsolete

>#include <link.h>
>#include <stdint.h>
>#include <stdio.h>
>#include <stdlib.h>
>#include <dlfcn.h>
>
>/**
> * mwe.c
> * Compile via: 
> * gcc -rdynamic mwe.c -o mwe -g -D_GNU_SOURCE
> * or
> * clang -rdynamic mwe.c -o mwe -g -D_GNU_SOURCE 
>*/
>static int callback(struct dl_phdr_info *info, size_t size, void *data) {
>	//A simple callback function
> 	printf("Name: \"%s\" (%d segments)\n", info->dlpi_name, info->dlpi_phnum);
> 	return 0;
>}
>
>typedef int (*lib_func)(int (*callback)(struct dl_phdr_info *, size_t, void *), void* data);
>
>int call_from_libc(){
>	/**
>	 * Calls dl_iterate_phdr indirectly by loading libc via dlopen
>	 * */
>	void     *handle  = NULL;
>	lib_func  func    = NULL;
>	handle = dlopen("/lib/libc.so.7",RTLD_NOW|RTLD_NOLOAD);// Put the name of your libc shared object
>	if (handle == NULL){
>		fprintf(stderr, "Unable to open lib: %s\n", dlerror());
>		return -1;
>	 }
>	func = dlsym(handle, "dl_iterate_phdr");
>
>	if (func == NULL) {
>		fprintf(stderr, "Unable to get symbol\n");
>		return -1;
>	}
>
>	func(callback, NULL);
>	return 0;
>}
>
>int main(int argc, char *argv[]) {
>	printf("Direct call:\n");
> 	dl_iterate_phdr(callback, NULL);//It works
>
>	printf("Indirect call:\n");
> 	call_from_libc();//It causes 'ld-elf.so.1: Can't find module with TLS index 1'
>
> 	exit(EXIT_SUCCESS);
>}

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Attachments on bug 272992: 243919