linux-kernel - [PATCH 4.9 018/207] x86/irq: Ensure PI wakeup handler is unregistered before module unload

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: <20211124115704.560465623@linuxfoundation.org>
Date:   Wed, 24 Nov 2021 12:54:49 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Subject: [PATCH 4.9 018/207] x86/irq: Ensure PI wakeup handler is unregistered before module unload

From: Sean Christopherson <seanjc@...gle.com>

commit 6ff53f6a438f72998f56e82e76694a1df9d1ea2c upstream.

Add a synchronize_rcu() after clearing the posted interrupt wakeup handler
to ensure all readers, i.e. in-flight IRQ handlers, see the new handler
before returning to the caller.  If the caller is an exiting module and
is unregistering its handler, failure to wait could result in the IRQ
handler jumping into an unloaded module.

The registration path doesn't require synchronization, as it's the
caller's responsibility to not generate interrupts it cares about until
after its handler is registered.

Fixes: f6b3c72c2366 ("x86/irq: Define a global vector for VT-d Posted-Interrupts")
Cc: stable@...r.kernel.org
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
Message-Id: <20211009001107.3936588-2-seanjc@...gle.com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/x86/kernel/irq.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/arch/x86/kernel/irq.c
+++ b/arch/x86/kernel/irq.c
@@ -284,8 +284,10 @@ void kvm_set_posted_intr_wakeup_handler(
 {
 	if (handler)
 		kvm_posted_intr_wakeup_handler = handler;
-	else
+	else {
 		kvm_posted_intr_wakeup_handler = dummy_handler;
+		synchronize_rcu();
+	}
 }
 EXPORT_SYMBOL_GPL(kvm_set_posted_intr_wakeup_handler);