Re: [RFC PATCH v2 4/7] csu: Fix standard fds' mode

[Paul Eggert <eggert@cs.ucla.edu>]

On 2023-04-20 05:06, Cristian Rodríguez via Libc-alpha wrote:
> Exactly, my understanding is that it is a futile exercise ..if one
> sufficient privilege at that stage one can do whatever is desired..  why
> even bother messing with the standard fds..

Making stdin unreadable is not meant to thwart a root-privileged 
attacker. As the comment in check_one_fd says, it's merely meant to 
catch bugs in programs that accidentally (for example) read from 
standard input even though there is no standard input. If standard input 
is /dev/null and readable, these buggy programs silently behave as if 
the input is the empty file, which is likely incorrect. In contrast, if 
standard input is not readable, these buggy programs will get a read 
error, which is more likely to cause them to report an error and alert 
users of the bug.

So let's leave glibc/csu/check_fds.c alone: it serves a useful purpose.

PS. Sorry if this email is duplicate; I had mail server problems.