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* [PATCH] acpi: pcihp: fix left shift undefined behavior in acpi_pcihp_eject_slot()
@ 2020-03-26 13:56 Igor Mammedov
  2020-03-26 13:58 ` Michael S. Tsirkin
  0 siblings, 1 reply; 2+ messages in thread
From: Igor Mammedov @ 2020-03-26 13:56 UTC (permalink / raw)
  To: qemu-devel; +Cc: peter.maydell, mst

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>
---
 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;
     }
 
-- 
2.18.1



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2020-03-26 13:56 [PATCH] acpi: pcihp: fix left shift undefined behavior in acpi_pcihp_eject_slot() Igor Mammedov
2020-03-26 13:58 ` Michael S. Tsirkin

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