linux-kernel - Re: [PATCH 2/4] binder: migrate ioctl to new PF_SPAM

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20240418081222.3871629-1-aliceryhl@google.com>
Date: Thu, 18 Apr 2024 08:12:22 +0000
From: Alice Ryhl <aliceryhl@...gle.com>
To: cmllamas@...gle.com
Cc: aliceryhl@...gle.com, arve@...roid.com, brauner@...nel.org, 
	gregkh@...uxfoundation.org, joel@...lfernandes.org, kernel-team@...roid.com, 
	linux-kernel@...r.kernel.org, maco@...roid.com, surenb@...gle.com, 
	tkjos@...roid.com
Subject: Re: [PATCH 2/4] binder: migrate ioctl to new PF_SPAM_DETECTION

Carlos Llamas <cmllamas@...gle.com> writes:
> @@ -5553,7 +5553,8 @@ static long binder_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
>  			goto err;
>  		}
>  		binder_inner_proc_lock(proc);
> -		proc->oneway_spam_detection_enabled = (bool)enable;
> +		proc->flags &= ~PF_SPAM_DETECTION;
> +		proc->flags |= enable & PF_SPAM_DETECTION;

The bitwise and in `enable & PF_SPAM_DETECTION` only works because
PF_SPAM_DETECTION happens to be equal to 1. This seems pretty fragile to
me. Would you be willing to do this instead?

proc->flags &= ~PF_SPAM_DETECTION;
if (enable)
	proc->flags |= PF_SPAM_DETECTION;


Carlos Llamas <cmllamas@...gle.com> writes:
> -			if (proc->oneway_spam_detection_enabled &&
> -				   w->type == BINDER_WORK_TRANSACTION_ONEWAY_SPAM_SUSPECT)
> +			if (proc->flags & PF_SPAM_DETECTION &&
> +			    w->type == BINDER_WORK_TRANSACTION_ONEWAY_SPAM_SUSPECT)

Maybe I am just not sufficiently familiar with C, but I had to look up
the operator precedence rules for this one. Could we add parenthesises
around `proc->flags & PF_SPAM_DETECTION`? Or even define a macro for it?

Alice