From fed33bd175f663cc8c13f8a490a4f35a19756cfe Mon Sep 17 00:00:00 2001 From: Vladimir Sementsov-Ogievskiy Date: Fri, 11 Oct 2019 12:07:07 +0300 Subject: [PATCH] hbitmap: handle set/reset with zero length Passing zero length to these functions leads to unpredicted results. Zero-length set/reset may occur in active-mirror, on zero-length write (which is unlikely, but not guaranteed to never happen). Let's just do nothing on zero-length request. Signed-off-by: Vladimir Sementsov-Ogievskiy Message-id: 20191011090711.19940-2-vsementsov@virtuozzo.com Reviewed-by: Max Reitz Cc: qemu-stable@nongnu.org Signed-off-by: Max Reitz --- util/hbitmap.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/util/hbitmap.c b/util/hbitmap.c index 66db87c6ff..242c6e519c 100644 --- a/util/hbitmap.c +++ b/util/hbitmap.c @@ -387,6 +387,10 @@ void hbitmap_set(HBitmap *hb, uint64_t start, uint64_t count) uint64_t first, n; uint64_t last = start + count - 1; + if (count == 0) { + return; + } + trace_hbitmap_set(hb, start, count, start >> hb->granularity, last >> hb->granularity); @@ -478,6 +482,10 @@ void hbitmap_reset(HBitmap *hb, uint64_t start, uint64_t count) uint64_t last = start + count - 1; uint64_t gran = 1ULL << hb->granularity; + if (count == 0) { + return; + } + assert(QEMU_IS_ALIGNED(start, gran)); assert(QEMU_IS_ALIGNED(count, gran) || (start + count == hb->orig_size));