[libvirt] [PATCH] util: fix off-by-one when expanding a bitmap

[Martin Kletzander]

On Mon, Jan 30, 2017 at 04:19:55PM +0100, Ján Tomko wrote:
>To make sure bit 'b' fits into the bitmap, we need to allocate b+1
>bits, since we number from 0.
>
>Adjust the bitmap test to use a multiple of 8 to catch this
>invalid write.

If I apply only the test hunks and not the actual fix, the tests don't
fail for me.  Am I missing something?  If yes, it'd be nice to add it to
the commit message.

>---
> src/util/virbitmap.c  | 2 +-
> tests/virbitmaptest.c | 6 +++---
> 2 files changed, 4 insertions(+), 4 deletions(-)
>
>diff --git a/src/util/virbitmap.c b/src/util/virbitmap.c
>index 0c04f1a..1b47d74 100644
>--- a/src/util/virbitmap.c
>+++ b/src/util/virbitmap.c
>@@ -187,7 +187,7 @@ int virBitmapSetBit(virBitmapPtr bitmap, size_t b)
>  */
> static int virBitmapExpand(virBitmapPtr map, size_t b)
> {
>-    size_t new_len = VIR_DIV_UP(b, VIR_BITMAP_BITS_PER_UNIT);
>+    size_t new_len = VIR_DIV_UP(b + 1, VIR_BITMAP_BITS_PER_UNIT);
>
>     /* resize the memory if necessary */
>     if (map->map_len < new_len) {
>diff --git a/tests/virbitmaptest.c b/tests/virbitmaptest.c
>index a17ef82..c2a06df 100644
>--- a/tests/virbitmaptest.c
>+++ b/tests/virbitmaptest.c
>@@ -639,15 +639,15 @@ test12(const void *opaque ATTRIBUTE_UNUSED)
>
>     TEST_MAP(0, "");
>
>-    if (virBitmapSetBitExpand(map, 100) < 0)
>+    if (virBitmapSetBitExpand(map, 120) < 0)
>         goto cleanup;
>
>-    TEST_MAP(101, "100");
>+    TEST_MAP(121, "120");
>
>     if (virBitmapClearBitExpand(map, 150) < 0)
>         goto cleanup;
>
>-    TEST_MAP(151, "100");
>+    TEST_MAP(151, "120");
>
>     virBitmapFree(map);
>     if (virBitmapParseUnlimited("34,1023", &map) < 0)
>--
>2.10.2
>
>--
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