From 3c9fd43da473a324f6cc7a0d3db58f651a2d262c Mon Sep 17 00:00:00 2001
From: Prasad J Pandit <pjp@fedoraproject.org>
Date: Fri, 26 Oct 2018 18:03:58 +0530
Subject: [PATCH] ppc/pnv: check size before data buffer access
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While performing PowerNV memory r/w operations, the access length
'sz' could exceed the data[4] buffer size. Add check to avoid OOB
access.

Reported-by: Moguofang <moguofang@huawei.com>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

CVE: CVE-2018-18954
Upstream-Status: Backport
[https://git.qemu.org/?p=qemu.git;a=commit;h=d07945e78eb6b593cd17a4640c1fc9eb35e3245d]

Signed-off-by: Dan Tran <dantran@microsoft.com>
---
 hw/ppc/pnv_lpc.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/hw/ppc/pnv_lpc.c b/hw/ppc/pnv_lpc.c
index d7721320a2..172a915cfc 100644
--- a/hw/ppc/pnv_lpc.c
+++ b/hw/ppc/pnv_lpc.c
@@ -155,9 +155,15 @@ static void pnv_lpc_do_eccb(PnvLpcController *lpc, uint64_t cmd)
     /* XXX Check for magic bits at the top, addr size etc... */
     unsigned int sz = (cmd & ECCB_CTL_SZ_MASK) >> ECCB_CTL_SZ_LSH;
     uint32_t opb_addr = cmd & ECCB_CTL_ADDR_MASK;
-    uint8_t data[4];
+    uint8_t data[8];
     bool success;
 
+    if (sz > sizeof(data)) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+            "ECCB: invalid operation at @0x%08x size %d\n", opb_addr, sz);
+        return;
+    }
+
     if (cmd & ECCB_CTL_READ) {
         success = opb_read(lpc, opb_addr, data, sz);
         if (success) {
-- 
2.22.0.vfs.1.1.57.gbaf16c8

