From: Steffen Eiden <seiden@linux.ibm.com>
To: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
linux-s390@vger.kernel.org, borntraeger@de.ibm.com,
frankja@linux.ibm.com, david@kernel.org, nrb@linux.ibm.com,
schlameuss@linux.ibm.com, gra@linux.ibm.com
Subject: Re: [PATCH v2 1/7] KVM: s390: Fix unlikely NULL gmap dereference
Date: Tue, 14 Jul 2026 10:32:13 +0200 [thread overview]
Message-ID: <20260714083213.55132-H-seiden@linux.ibm.com> (raw)
In-Reply-To: <20260713150857.269954-2-imbrenda@linux.ibm.com>
On Mon, Jul 13, 2026 at 05:08:51PM +0200, Claudio Imbrenda wrote:
> When creating a new vCPU, kvm_vm_ioctl_create_vcpu() will call
> kvm_arch_vcpu_postcreate() after the file descriptor for the new vCPU
> has been created. The new file descriptor has not been returned yet,
> but a malicious userspace program could try to guess it.
>
> If a malicious userspace program manages to start the newly created vCPU
> before kvm_arch_vcpu_postcreate() is called, __vcpu_run() will try to
> dereference vcpu->arch.gmap and trigger a NULL pointer dereference.
>
> Fix this by moving the initialization of vcpu->arch.gmap into
> kvm_arch_vcpu_create(), which is called before the file descriptor for
> the vCPU is created.
>
> Fixes: dafd032a15f8 ("KVM: s390: move vcpu specific initalization to a later point")
> Fixes: e38c884df921 ("KVM: s390: Switch to new gmap")
> Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Steffen Eiden <seiden@linux.ibm.com>
next prev parent reply other threads:[~2026-07-14 8:32 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-13 15:08 [PATCH v2 0/7] KVM: s390: Misc fixes Claudio Imbrenda
2026-07-13 15:08 ` [PATCH v2 1/7] KVM: s390: Fix unlikely NULL gmap dereference Claudio Imbrenda
2026-07-13 15:47 ` sashiko-bot
2026-07-14 8:32 ` Steffen Eiden [this message]
2026-07-14 13:23 ` Janosch Frank
2026-07-13 15:08 ` [PATCH v2 2/7] KVM: s390: Return -EFAULT instead of PGM_ADDRESSING Claudio Imbrenda
2026-07-13 15:27 ` sashiko-bot
2026-07-14 8:44 ` Steffen Eiden
2026-07-13 15:08 ` [PATCH v2 3/7] KVM: s390: Fix race in __do_essa() Claudio Imbrenda
2026-07-13 15:31 ` sashiko-bot
2026-07-13 15:08 ` [PATCH v2 4/7] KVM: s390: cmma: Fix dirty tracking when removing memslot Claudio Imbrenda
2026-07-13 15:58 ` sashiko-bot
2026-07-13 15:08 ` [PATCH v2 5/7] KVM: s390: ucontrol: Add missing locking around gmap_remove_child() Claudio Imbrenda
2026-07-13 15:29 ` sashiko-bot
2026-07-13 15:08 ` [PATCH v2 6/7] KVM: s390: Fix overclearing ESCA in case of error Claudio Imbrenda
2026-07-13 15:31 ` sashiko-bot
2026-07-14 12:48 ` Janosch Frank
2026-07-14 12:51 ` Christian Borntraeger
2026-07-13 15:08 ` [PATCH v2 7/7] KVM: s390: Return -EINTR if a signal was pending while faulting-in Claudio Imbrenda
2026-07-13 15:33 ` sashiko-bot
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