From: Steffen Eiden <seiden@linux.ibm.com>
To: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org,
kvm@vger.kernel.org, david@redhat.com, frankja@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 14:16:20 +0200 [thread overview]
Message-ID: <20250805121620.40333-A-seiden@linux.ibm.com> (raw)
In-Reply-To: <20250805111446.40937-2-imbrenda@linux.ibm.com>
On Tue, Aug 05, 2025 at 01:14:45PM +0200, 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: Steffen Eiden <seiden@linux.ibm.com>
next prev parent reply other threads:[~2025-08-05 12:16 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
2025-08-05 12:16 ` Steffen Eiden [this message]
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20250805121620.40333-A-seiden@linux.ibm.com \
--to=seiden@linux.ibm.com \
--cc=borntraeger@de.ibm.com \
--cc=david@redhat.com \
--cc=frankja@linux.ibm.com \
--cc=hca@linux.ibm.com \
--cc=imbrenda@linux.ibm.com \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-s390@vger.kernel.org \
--cc=mhartmay@linux.ibm.com \
--cc=nrb@linux.ibm.com \
--cc=nsg@linux.ibm.com \
--cc=schlameuss@linux.ibm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox