From f7d6a635fa3b7797f9d072e280f065bf3cfcd24d Mon Sep 17 00:00:00 2001
From: Prasad J Pandit <pjp@fedoraproject.org>
Date: Thu, 4 Jun 2020 17:05:25 +0530
Subject: [PATCH] pci: assert configuration access is within bounds
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While accessing PCI configuration bytes, assert that
'address + len' is within PCI configuration space.

Generally it is within bounds. This is more of a defensive
assert, in case a buggy device was to send 'address' which
may go out of bounds.

Suggested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Message-Id: <20200604113525.58898-1-ppandit@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

Upstream-Status: Backport [f7d6a635fa3b7797f9d072e280f065bf3cfcd24d]
CVE: CVE-2020-13791
Signed-off-by: Sakib Sajal <sakib.sajal@windriver.com>
---
 hw/pci/pci.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/hw/pci/pci.c b/hw/pci/pci.c
index 70c66965f5..7bf2ae6d92 100644
--- a/hw/pci/pci.c
+++ b/hw/pci/pci.c
@@ -1381,6 +1381,8 @@ uint32_t pci_default_read_config(PCIDevice *d,
 {
     uint32_t val = 0;
 
+    assert(address + len <= pci_config_size(d));
+
     if (pci_is_express_downstream_port(d) &&
         ranges_overlap(address, len, d->exp.exp_cap + PCI_EXP_LNKSTA, 2)) {
         pcie_sync_bridge_lnk(d);
@@ -1394,6 +1396,8 @@ void pci_default_write_config(PCIDevice *d, uint32_t addr, uint32_t val_in, int
     int i, was_irq_disabled = pci_irq_disabled(d);
     uint32_t val = val_in;
 
+    assert(addr + l <= pci_config_size(d));
+
     for (i = 0; i < l; val >>= 8, ++i) {
         uint8_t wmask = d->wmask[addr + i];
         uint8_t w1cmask = d->w1cmask[addr + i];
-- 
2.20.1