[libvirt] [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(a)amd.com>
---
diff --git a/src/util/virbitmap.c b/src/util/virbitmap.c
index d074f29e54..021174cbb3 100644
--- a/src/util/virbitmap.c
+++ b/src/util/virbitmap.c
@@ -824,11 +824,15 @@ 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++) {