From: David Hildenbrand <david@redhat.com>
To: Claudio Imbrenda <imbrenda@linux.ibm.com>, linux-kernel@vger.kernel.org
Cc: linux-s390@vger.kernel.org, kvm@vger.kernel.org,
frankja@linux.ibm.com, seiden@linux.ibm.com, nsg@linux.ibm.com,
nrb@linux.ibm.com, schlameuss@linux.ibm.com, hca@linux.ibm.com,
mhartmay@linux.ibm.com, borntraeger@de.ibm.com
Subject: Re: [PATCH v1 1/2] KVM: s390: Fix incorrect usage of mmu_notifier_register()
Date: Tue, 5 Aug 2025 14:09:11 +0200 [thread overview]
Message-ID: <0bd8a969-e8e0-4eb6-97a2-300fc322f8a2@redhat.com> (raw)
In-Reply-To: <20250805111446.40937-2-imbrenda@linux.ibm.com>
On 05.08.25 13:14, Claudio Imbrenda wrote:
> If mmu_notifier_register() fails, for example because a signal was
> pending, the mmu_notifier will not be registered. But when the VM gets
> destroyed, it will get unregistered anyway and that will cause one
> extra mmdrop(), which will eventually cause the mm of the process to
> be freed too early, and cause a use-after free.
>
> This bug happens rarely, and only when secure guests are involved.
>
> The solution is to check the return value of mmu_notifier_register()
> and return it to the caller (ultimately it will be propagated all the
> way to userspace). In case of -EINTR, userspace will try again.
>
> Fixes: ca2fd0609b5d ("KVM: s390: pv: add mmu_notifier")
> Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
> ---
Reviewed-by: David Hildenbrand <david@redhat.com>
--
Cheers,
David / dhildenb
next prev parent reply other threads:[~2025-08-05 12:09 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-08-05 11:14 [PATCH v1 0/2] KVM: s390: Fix two bugs Claudio Imbrenda
2025-08-05 11:14 ` [PATCH v1 1/2] KVM: s390: Fix incorrect usage of mmu_notifier_register() Claudio Imbrenda
2025-08-05 11:54 ` Christian Borntraeger
2025-08-05 12:09 ` David Hildenbrand [this message]
2025-08-05 12:16 ` Steffen Eiden
2025-08-05 13:07 ` Christoph Schlameuss
2025-08-05 11:14 ` [PATCH v1 2/2] KVM: s390: Fix FOLL_*/FAULT_FLAG_* confusion Claudio Imbrenda
2025-08-05 11:44 ` Christian Borntraeger
2025-08-05 11:59 ` Claudio Imbrenda
2025-08-05 12:11 ` David Hildenbrand
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