linux-kernel - Re: [PATCH 6/8] x86/fpu: Make sure x86_task_fpu() doesn't get called for PF_KTHREAD|PF_USER

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: <bc06b0e7-8325-4044-93cd-a365ea745c0a@intel.com>
Date: Fri, 11 Apr 2025 08:22:16 -0700
From: "Chang S. Bae" <chang.seok.bae@...el.com>
To: Ingo Molnar <mingo@...nel.org>, <linux-kernel@...r.kernel.org>
CC: Andy Lutomirski <luto@...capital.net>, Dave Hansen <dave@...1.net>, "Brian
 Gerst" <brgerst@...il.com>, Peter Zijlstra <peterz@...radead.org>, "Borislav
 Petkov" <bp@...en8.de>, "H . Peter Anvin" <hpa@...or.com>, Linus Torvalds
	<torvalds@...ux-foundation.org>, Oleg Nesterov <oleg@...hat.com>, "Thomas
 Gleixner" <tglx@...utronix.de>
Subject: Re: [PATCH 6/8] x86/fpu: Make sure x86_task_fpu() doesn't get called
 for PF_KTHREAD|PF_USER_WORKER tasks during exit

On 4/9/2025 2:11 PM, Ingo Molnar wrote:
>   
>   void arch_release_task_struct(struct task_struct *tsk)
>   {
> -	if (fpu_state_size_dynamic())
> +	if (fpu_state_size_dynamic() && !(current->flags & (PF_KTHREAD | PF_USER_WORKER)))
>   		fpstate_free(x86_task_fpu(tsk));
>   }

Looks like the AMX system couldn't boot properly, and I found that 
referencing tsk->flags here resolves the issue.

Thanks,
Chang