From: Jirka Kosina (jikosjikos.cz)
Date: Fri Nov 12 2004 - 06:08:56 CST

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On Wed, 10 Nov 2004, Paul Starzetz wrote:

> Synopsis: Linux kernel binfmt_elf loader vulnerabilities
> Product: Linux kernel
> Version: 2.4 up to to and including 2.4.27, 2.6 up to to and
> including 2.6.8

And also 2.6.9.

> 3) bad return value vulnerability while mapping the program intrepreter
> into memory:
>
> 301: retval = kernel_read(interpreter,interp_elf_ex->e_phoff,(char *)elf_phdata,size);
> error = retval;
> if (retval < 0)
> goto out_close;
> eppnt = elf_phdata;
> for (i=0; i<interp_elf_ex->e_phnum; i++, eppnt++) {
> map_addr = elf_map(interpreter, load_addr + vaddr, eppnt, elf_prot, elf_type);
> 322: if (BAD_ADDR(map_addr))
> goto out_close;
> out_close:
> kfree(elf_phdata);
> out:
> return error;
> }

This bug is only present in 2.4 version, in 2.6 kernels we can see

        retval = kernel_read(interpreter,interp_elf_ex->e_phoff,(char *)elf_phdata,size);
        error = retval;
        if (retval < 0)
                goto out_close;
[... cutted ... ]
            map_addr = elf_map(interpreter, load_addr + vaddr, eppnt, elf_prot, elf_type);
            error = map_addr;
            if (BAD_ADDR(map_addr))
                goto out_close;

--
JiKos.

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