diff options
| author | Tuguoyi <tu.guoyi@h3c.com> | 2020-08-05 09:22:58 +0000 |
|---|---|---|
| committer | Peter Maydell <peter.maydell@linaro.org> | 2020-08-05 14:56:11 +0100 |
| commit | 348fcc4f7ace1718006e646078d88c8cd8c1d97e (patch) | |
| tree | f694a2839104f147abfff6516ca21deca7709ca7 | |
| parent | 616dab9afc904923554c151011c817ff3191ecde (diff) | |
qcow2-cluster: Fix integer left shift error in qcow2_alloc_cluster_link_l2()
When calculating the offset, the result of left shift operation will be promoted
to type int64 automatically because the left operand of + operator is uint64_t.
but the result after integer promotion may be produce an error value for us and
trigger the following asserting error.
For example, consider i=0x2000, cluster_bits=18, the result of left shift
operation will be 0x80000000. Cause argument i is of signed integer type,
the result is automatically promoted to 0xffffffff80000000 which is not
we expected
The way to trigger the assertion error:
qemu-img create -f qcow2 -o preallocation=full,cluster_size=256k tmpdisk 10G
This patch fix it by casting @i to uint64_t before doing left shift operation
Signed-off-by: Guoyi Tu <tu.guoyi@h3c.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 81ba90fe0c014f269621c283269b42ad@h3c.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
| -rw-r--r-- | block/qcow2-cluster.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c index a677ba9f5c..550850b264 100644 --- a/block/qcow2-cluster.c +++ b/block/qcow2-cluster.c @@ -980,7 +980,7 @@ int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m) assert(l2_index + m->nb_clusters <= s->l2_slice_size); for (i = 0; i < m->nb_clusters; i++) { - uint64_t offset = cluster_offset + (i << s->cluster_bits); + uint64_t offset = cluster_offset + ((uint64_t)i << s->cluster_bits); /* if two concurrent writes happen to the same unallocated cluster * each write allocates separate cluster and writes data concurrently. * The first one to complete updates l2 table with pointer to its |