From 806c01fea005e3887ad74efa3ecbab8294c0ddca Mon Sep 17 00:00:00 2001
Message-Id: <806c01fea005e3887ad74efa3ecbab8294c0ddca@dist-git>
From: "Allen, John" <John.Allen@amd.com>
Date: Fri, 26 Apr 2019 15:12:01 +0200
Subject: [PATCH] Handle copying bitmaps to larger data buffers

If a bitmap of a shorter length than the data buffer is passed to
virBitmapToDataBuf, it will read off the end of the bitmap and copy junk
into the returned buffer. Add a check to only copy the length of the
bitmap to the buffer.

The problem can be observed after setting a vcpu affinity using the vcpupin
command on a system with a large number of cores:
  # virsh vcpupin example_domain 0 0
  # virsh vcpupin example_domain 0
     VCPU   CPU Affinity
    ---------------------------
     0      0,192,197-198,202

Signed-off-by: John Allen <john.allen@amd.com>
(cherry picked from commit 51f9f80d350e633adf479c6a9b3c55f82ca9cbd4)

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1703159

Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
Message-Id: <8c72d73f39288e0a38d72481e771d1df53d593a3.1556284274.git.phrdina@redhat.com>
Reviewed-by: Andrea Bolognani <abologna@redhat.com>
---
 src/util/virbitmap.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/util/virbitmap.c b/src/util/virbitmap.c
index 0cc5292d8c..0bc0d068bb 100644
--- a/src/util/virbitmap.c
+++ b/src/util/virbitmap.c
@@ -832,11 +832,15 @@ virBitmapToDataBuf(virBitmapPtr bitmap,
                    unsigned char *bytes,
                    size_t len)
 {
+    size_t nbytes = bitmap->map_len * (VIR_BITMAP_BITS_PER_UNIT / CHAR_BIT);
     unsigned long *l;
     size_t i, j;
 
     memset(bytes, 0, len);
 
+    /* If bitmap and buffer differ in size, only fill to the smaller length */
+    len = MIN(len, nbytes);
+
     /* htole64 is not provided by gnulib, so we do the conversion by hand */
     l = bitmap->map;
     for (i = j = 0; i < len; i++, j++) {
-- 
2.21.0