Re: [RFC c/r 4/4] c/r: prctl: Extend PR_SET_MM to set up moremm_struct entries
From: Kees Cook
Date: Fri Jan 27 2012 - 13:37:07 EST
On Fri, Jan 27, 2012 at 9:53 AM, Cyrill Gorcunov <gorcunov@xxxxxxxxxx> wrote:
> + if (opt == PR_SET_MM_START_STACK)
> + mm->start_stack = addr;
> + else if (opt == PR_SET_MM_ARG_START)
> + mm->arg_start = addr;
> + else if (opt == PR_SET_MM_ARG_END)
> + mm->arg_end = addr;
> + else if (opt == PR_SET_MM_ENV_START)
> + mm->env_start = addr;
> + else if (opt == PR_SET_MM_ENV_END)
> + mm->env_end = addr;
> + break;
Why not a switch statement here? Not that it really matters. :)
> +
> + case PR_SET_MM_AUXV:
> + if (arg4 > sizeof(mm->saved_auxv))
> + goto out;
> + up_read(&mm->mmap_sem);
> +
> + error = -EFAULT;
> + if (!copy_from_user(mm->saved_auxv, (const void __user *)addr, arg4))
> + error = 0;
> +
> + return error;
Is the mmap_sem released here because of the copy_from_user()? Is it
still safe to write to saved_auxv?
-Kees
--
Kees Cook
ChromeOS Security
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