File 0189-spapr_pci-add-spapr-msi-read-method.patch of Package qemu.28156

From: Prasad J Pandit <pjp@fedoraproject.org>
Date: Tue, 11 Aug 2020 17:11:30 +0530
Subject: spapr_pci: add spapr msi read method

Git-commit: 921604e175b8ec06c39503310e7b3ec1e3eafe9e
References: bsc#1173612, CVE-2020-15469

Add spapr msi mmio read method to avoid NULL pointer dereference
issue.

Reported-by: Lei Sun <slei.casper@gmail.com>
Acked-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Li Qiang <liq3ea@gmail.com>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Message-Id: <20200811114133.672647-7-ppandit@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Bruce Rogers <brogers@suse.com>
---
 hw/ppc/spapr_pci.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
index 2374d55fc112bfef41e32100638d..7c39591da77ede087f00aa7c2dc4 100644
--- a/hw/ppc/spapr_pci.c
+++ b/hw/ppc/spapr_pci.c
@@ -49,6 +49,7 @@
 #include "sysemu/kvm.h"
 #include "sysemu/hostmem.h"
 #include "sysemu/numa.h"
+#include "qemu/log.h"
 
 /* Copied from the kernel arch/powerpc/platforms/pseries/msi.c */
 #define RTAS_QUERY_FN           0
@@ -752,6 +753,12 @@ static PCIINTxRoute spapr_route_intx_pin_to_irq(void *opaque, int pin)
     return route;
 }
 
+static uint64_t spapr_msi_read(void *opaque, hwaddr addr, unsigned size)
+{
+    qemu_log_mask(LOG_GUEST_ERROR, "%s: invalid access\n", __func__);
+    return 0;
+}
+
 /*
  * MSI/MSIX memory region implementation.
  * The handler handles both MSI and MSIX.
@@ -769,8 +776,11 @@ static void spapr_msi_write(void *opaque, hwaddr addr,
 }
 
 static const MemoryRegionOps spapr_msi_ops = {
-    /* There is no .read as the read result is undefined by PCI spec */
-    .read = NULL,
+    /*
+     * .read result is undefined by PCI spec.
+     * define .read method to avoid assert failure in memory_region_init_io
+     */
+    .read = spapr_msi_read,
     .write = spapr_msi_write,
     .endianness = DEVICE_LITTLE_ENDIAN
 };