Bug 145497

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Description of problem:
Invoking the gelf_checksum() function results in a SIGSEGV. Debugging
shows this is due to the following elf_getdata() call (in
elf32_checksum.c) returning a NULL pointer; which causes the
subsequent dereference to get the d_type structure member to generate
a SIGSEGV:

      while ((data = INTUSE(elf_getdata) (scn, data)) != NULL)
        /* If the file byte order is the same as the host byte order
           process the buffer directly.  If the data is just a stream
           of bytes which the library will not convert we can use it
           as well.  */
        if (likely (same_byte_order) || data->d_type == ELF_T_BYTE)

Test program for reproducing the failure:

#include <stdio.h>
#include <unistd.h>
#include <limits.h>
#include <libelf.h>
#include <fcntl.h>

main(int argc, char **argv) {
    int i, fd;
    long tmp_checksum;
    Elf *elf;

    elf_version(EV_CURRENT);  /* Initialize ELF version */

    printf("Attempting to generate elf_checksum for %s.\n",argv[1]);
    fd = open(argv[1], O_RDONLY);
    if (fd == -1) { /* open of file failed */
            printf("Unable to open file %s.\n",argv[1]);
            exit(0);
    }
    else {
            printf("Calling elf_begin().\n");
            elf = elf_begin(fd, ELF_C_READ, NULL);
            printf("elf_begin returned %p. Calling
lf_checksum().\n",elf);      
    
            //tmp_checksum = gelf_checksum(elf);
            tmp_checksum = elf64_checksum(elf);
            printf("After gelf_checksum() w/checksum %d.\n",tmp_checksum);
            printf("Calling elf_end().\n");
            elf_end(elf);
            close(fd);
    }
}


Version-Release number of selected component (if applicable):
elfutils-0.91-3

How reproducible:
Always

Steps to Reproduce:
1. cc -o gelf_checksum gelf_checksum.c -lelf
2. ./gelf_checksum gelf_checksum

    

Actual Results:  Attempting to generate elf_checksum for gelf_checksum.
Calling elf_begin().
elf_begin returned 0x9d5e008. Calling lf_checksum().
Segmentation fault


Expected Results:  The message

    After gelf_checksum() w/checksum %d

rather than a segmentation fault.

Additional info:

Also reproduced on FC3.