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a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1772454866; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=tziAZ1N/0eyP13+sACHlLrdutEwgbzNrSyw4EPjfTo4=; b=ZeC2chbvUwWXJa6+ERSKLqlC71bf6TnhhfTSkjNxLR9xQFbHjAsSq34d6fkis8AtOXzdGT qf+fDrLw8nuW7nT7TTQsOK3qZ9APJ/otv+0etUIjOg7VxRHRWYmeqLteMm1BtWW9zVgqyE 6ek55lWW5hq3Iuw7zgW/Hb2/vHfAFkw= X-MC-Unique: BgNMhUOIMWKJyyZGfolBxw-1 X-Mimecast-MFC-AGG-ID: BgNMhUOIMWKJyyZGfolBxw_1772454861 From: Thomas Huth To: Peter Maydell Cc: qemu-devel@nongnu.org, Aby Sam Ross , Eric Farman , Matthew Rosato , Farhan Ali , Halil Pasic Subject: [PULL 01/10] s390x/pci: prevent null pointer dereference during zpci hot unplug Date: Mon, 2 Mar 2026 13:34:04 +0100 Message-ID: <20260302123413.274700-2-thuth@redhat.com> In-Reply-To: <20260302123413.274700-1-thuth@redhat.com> References: <20260302123413.274700-1-thuth@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; 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charset="utf-8" From: Aby Sam Ross vfio-pci hostdev realize during zpci hot plug fails (in `vfio_pci_realize()= `) if the vfio group file in `/dev/vfio/` lacks appropriate permissions and the hostdev[/properties] addition doesn't reach the point where it could be associated with previously added zpci device (in `s390_pcihost_plug()`). As a result, zpci iommu pointer remains null. The zpci hot unplug following= the failed hostdev addition assumes zpci iommu pointer was assigned and tries to make use of it to end the dma count resulting in a null pointer dereference. In the non-hotplug scenario, `qdev_unplug()` for the zpci device is not cal= led after hostdev addition failure and this issue is not encountered. All other uses of zpci iommu without null check happens after both the zpci= and hostdev(pci) devices are plugged and are safe from null dereference. Fixes: 37fa32de7073 ("s390x/pci: Honor DMA limits set by vfio") Signed-off-by: Aby Sam Ross Acked-by: Eric Farman Reviewed-by: Matthew Rosato Reviewed-by: Farhan Ali Suggested-by: Halil Pasic Message-ID: Signed-off-by: Thomas Huth --- hw/s390x/s390-pci-bus.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/hw/s390x/s390-pci-bus.c b/hw/s390x/s390-pci-bus.c index b438d63c444..3166b91c461 100644 --- a/hw/s390x/s390-pci-bus.c +++ b/hw/s390x/s390-pci-bus.c @@ -1248,7 +1248,7 @@ static void s390_pcihost_unplug(HotplugHandler *hotpl= ug_dev, DeviceState *dev, pbdev->fid =3D 0; QTAILQ_REMOVE(&s->zpci_devs, pbdev, link); g_hash_table_remove(s->zpci_table, &pbdev->idx); - if (pbdev->iommu->dma_limit) { + if (pbdev->iommu && pbdev->iommu->dma_limit) { s390_pci_end_dma_count(s, pbdev->iommu->dma_limit); } qdev_unrealize(dev); --=20 2.53.0