Any goto fail between having read nb_snapshots (returning a non-zero value) and allocating s->snapshots (through qcow2_read_snapshots()) results in qcow2_free_snapshots() being called, dereferencing s->snapshots which is still NULL.
Fix this by moving the reading of nb_snapshots right before the call to qcow2_read_snapshots(). Signed-off-by: Max Reitz <mre...@redhat.com> --- block/qcow2.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/block/qcow2.c b/block/qcow2.c index 6e5d98d..3e612a8 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -558,9 +558,6 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags, s->refcount_table_size = header.refcount_table_clusters << (s->cluster_bits - 3); - s->snapshots_offset = header.snapshots_offset; - s->nb_snapshots = header.nb_snapshots; - /* read the level 1 table */ s->l1_size = header.l1_size; @@ -637,6 +634,9 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags, bs->backing_file[len] = '\0'; } + s->snapshots_offset = header.snapshots_offset; + s->nb_snapshots = header.nb_snapshots; + ret = qcow2_read_snapshots(bs); if (ret < 0) { error_setg_errno(errp, -ret, "Could not read snapshots"); -- 1.8.4.2