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[PULL 04/10] acpi: pcihp: fix left shift undefined behavior in acpi_pcihp_eject_slot()

Michael S. Tsirkin posted 10 patches 5 years, 10 months ago

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Maintainers: Eduardo Habkost <ehabkost@redhat.com>, Igor Mammedov <imammedo@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>, Laurent Vivier <lvivier@redhat.com>, "Michael S. Tsirkin" <mst@redhat.com>, Eric Auger <eric.auger@redhat.com>, Marcel Apfelbaum <marcel.apfelbaum@gmail.com>, Amit Shah <amit@kernel.org>, "Marc-André Lureau" <marcandre.lureau@redhat.com>, Kevin Wolf <kwolf@redhat.com>, Max Reitz <mreitz@redhat.com>, Peter Maydell <peter.maydell@linaro.org>, Shannon Zhao <shannon.zhaosl@gmail.com>, Stefan Hajnoczi <stefanha@redhat.com>, Richard Henderson <rth@twiddle.net>

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[PULL 04/10] acpi: pcihp: fix left shift undefined behavior in acpi_pcihp_eject_slot()

Posted by Michael S. Tsirkin 5 years, 10 months ago

From: Igor Mammedov <imammedo@redhat.com>

Coverity spots subj in following guest triggered code path
  pci_write(, data = 0) -> acpi_pcihp_eject_slot(,slots = 0)
     uinst32_t slot = ctz32(slots)
     ...
     ... = ~(1U << slot)
where 'slot' value is 32 in case 'slots' bitmap is empty.
'slots' is a bitmap and empty one shouldn't  do anything
so return early doing nothing if resulted slot value is
not valid (i.e. not in 0-31 range)

Reported-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Message-Id: <20200326135624.32464-1-imammedo@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 hw/acpi/pcihp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/acpi/pcihp.c b/hw/acpi/pcihp.c
index 4dcef372bf..0dc963e983 100644
--- a/hw/acpi/pcihp.c
+++ b/hw/acpi/pcihp.c
@@ -154,7 +154,7 @@ static void acpi_pcihp_eject_slot(AcpiPciHpState *s, unsigned bsel, unsigned slo
 
     trace_acpi_pci_eject_slot(bsel, slot);
 
-    if (!bus) {
+    if (!bus || slot > 31) {
         return;
     }
 
-- 
MST