linux-kernel - [patch 12/21] x86/fpu: Do not leak fpstate pointer on fork

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: <20211013145322.817101108@linutronix.de>
Date:   Wed, 13 Oct 2021 16:55:43 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     x86@...nel.org, "Chang S. Bae" <chang.seok.bae@...el.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Arjan van de Ven <arjan@...ux.intel.com>,
        kvm@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>
Subject: [patch 12/21] x86/fpu: Do not leak fpstate pointer on fork

If fork fails early then the copied task struct would carry the fpstate
pointer of the parent task.

Not a problem right now, but later when dynamically allocated buffers are
available, keeping the pointer might result in freeing the parents
buffer. Set it to NULL which prevents that. If fork reaches clone_thread,
the pointer will be correctly set to the new task context.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
 arch/x86/kernel/process.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -87,6 +87,8 @@ int arch_dup_task_struct(struct task_str
 #ifdef CONFIG_VM86
 	dst->thread.vm86 = NULL;
 #endif
+	/* Drop the copied pointer to current's fpstate */
+	dst->thread.fpu.fpstate = NULL;
 	return 0;
 }