From 9daa72fa9d5ca947ced6664dd1eac0861a1e5123 Mon Sep 17 00:00:00 2001 From: Prasad J Pandit Date: Wed, 14 Oct 2020 15:00:20 +0800 Subject: [PATCH] pci: check bus pointer before dereference fix CVE-2020-25742 patch link: https://lists.nongnu.org/archive/html/qemu-devel/2020-09/msg05294.html While mapping IRQ level in pci_change_irq_level() routine, it does not check if pci_get_bus() returned a valid pointer. It may lead to a NULL pointer dereference issue. Add check to avoid it. -> https://ruhr-uni-bochum.sciebo.de/s/NNWP2GfwzYKeKwE?path=%2Flsi_nullptr1 ==1183858==Hint: address points to the zero page. #0 pci_change_irq_level hw/pci/pci.c:259 #1 pci_irq_handler hw/pci/pci.c:1445 #2 pci_set_irq hw/pci/pci.c:1463 #3 lsi_set_irq hw/scsi/lsi53c895a.c:488 #4 lsi_update_irq hw/scsi/lsi53c895a.c:523 #5 lsi_script_scsi_interrupt hw/scsi/lsi53c895a.c:554 #6 lsi_execute_script hw/scsi/lsi53c895a.c:1149 #7 lsi_reg_writeb hw/scsi/lsi53c895a.c:1984 #8 lsi_io_write hw/scsi/lsi53c895a.c:2146 ... Reported-by: Ruhr-University Signed-off-by: Prasad J Pandit --- ...check-bus-pointer-before-dereference.patch | 50 +++++++++++++++++++ 1 file changed, 50 insertions(+) create mode 100644 pci-check-bus-pointer-before-dereference.patch diff --git a/pci-check-bus-pointer-before-dereference.patch b/pci-check-bus-pointer-before-dereference.patch new file mode 100644 index 0000000..540caaf --- /dev/null +++ b/pci-check-bus-pointer-before-dereference.patch @@ -0,0 +1,50 @@ +From e393095e6d1456e2fb22f3cde3a9f0a307152562 Mon Sep 17 00:00:00 2001 +From: Prasad J Pandit +Date: Wed, 14 Oct 2020 15:00:20 +0800 +Subject: [PATCH] pci: check bus pointer before dereference + +fix CVE-2020-25742 + +patch link: https://lists.nongnu.org/archive/html/qemu-devel/2020-09/msg05294.html + +While mapping IRQ level in pci_change_irq_level() routine, +it does not check if pci_get_bus() returned a valid pointer. +It may lead to a NULL pointer dereference issue. Add check to +avoid it. + + -> https://ruhr-uni-bochum.sciebo.de/s/NNWP2GfwzYKeKwE?path=%2Flsi_nullptr1 + ==1183858==Hint: address points to the zero page. + #0 pci_change_irq_level hw/pci/pci.c:259 + #1 pci_irq_handler hw/pci/pci.c:1445 + #2 pci_set_irq hw/pci/pci.c:1463 + #3 lsi_set_irq hw/scsi/lsi53c895a.c:488 + #4 lsi_update_irq hw/scsi/lsi53c895a.c:523 + #5 lsi_script_scsi_interrupt hw/scsi/lsi53c895a.c:554 + #6 lsi_execute_script hw/scsi/lsi53c895a.c:1149 + #7 lsi_reg_writeb hw/scsi/lsi53c895a.c:1984 + #8 lsi_io_write hw/scsi/lsi53c895a.c:2146 + ... + +Reported-by: Ruhr-University +Signed-off-by: Prasad J Pandit +--- + hw/pci/pci.c | 3 +++ + 1 file changed, 3 insertions(+) + +diff --git a/hw/pci/pci.c b/hw/pci/pci.c +index de0fae10ab..df5a2c3294 100644 +--- a/hw/pci/pci.c ++++ b/hw/pci/pci.c +@@ -253,6 +253,9 @@ static void pci_change_irq_level(PCIDevice *pci_dev, int irq_num, int change) + PCIBus *bus; + for (;;) { + bus = pci_get_bus(pci_dev); ++ if (!bus) { ++ return; ++ } + irq_num = bus->map_irq(pci_dev, irq_num); + if (bus->set_irq) + break; +-- +2.23.0 +