diff options
| author | Paolo Bonzini <pbonzini@redhat.com> | 2012-05-04 12:32:04 +0200 |
|---|---|---|
| committer | James Bottomley <JBottomley@Parallels.com> | 2012-05-10 08:27:06 +0100 |
| commit | e4594bb50518eb89c447be97dabd5bd99f405d71 (patch) | |
| tree | f4e8d81b2b30cb8ab53207382c2841983954b833 | |
| parent | 3c8d9a957d0ae62c2815393a781ab7ff4d5205e7 (diff) | |
[SCSI] virtio_scsi: fix TMF use-after-free
Fix a use-after-free in the TMF path, where cmd may have been already
freed by virtscsi_complete_free when wait_for_completion restarts
executing virtscsi_tmf. Technically a race, but in practice the command
will always be freed long before the completion waiter is awoken.
The fix is to make callers specifying a completion responsible for
freeing the command in all cases.
Signed-off-by: Hu Tao <hutao@cn.fujitsu.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
| -rw-r--r-- | drivers/scsi/virtio_scsi.c | 24 |
1 files changed, 13 insertions, 11 deletions
diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c index efccd72c4a3..1b384311726 100644 --- a/drivers/scsi/virtio_scsi.c +++ b/drivers/scsi/virtio_scsi.c @@ -175,7 +175,8 @@ static void virtscsi_complete_free(void *buf) if (cmd->comp) complete_all(cmd->comp); - mempool_free(cmd, virtscsi_cmd_pool); + else + mempool_free(cmd, virtscsi_cmd_pool); } static void virtscsi_ctrl_done(struct virtqueue *vq) @@ -311,21 +312,22 @@ out: static int virtscsi_tmf(struct virtio_scsi *vscsi, struct virtio_scsi_cmd *cmd) { DECLARE_COMPLETION_ONSTACK(comp); - int ret; + int ret = FAILED; cmd->comp = ∁ - ret = virtscsi_kick_cmd(vscsi, vscsi->ctrl_vq, cmd, - sizeof cmd->req.tmf, sizeof cmd->resp.tmf, - GFP_NOIO); - if (ret < 0) - return FAILED; + if (virtscsi_kick_cmd(vscsi, vscsi->ctrl_vq, cmd, + sizeof cmd->req.tmf, sizeof cmd->resp.tmf, + GFP_NOIO) < 0) + goto out; wait_for_completion(&comp); - if (cmd->resp.tmf.response != VIRTIO_SCSI_S_OK && - cmd->resp.tmf.response != VIRTIO_SCSI_S_FUNCTION_SUCCEEDED) - return FAILED; + if (cmd->resp.tmf.response == VIRTIO_SCSI_S_OK || + cmd->resp.tmf.response == VIRTIO_SCSI_S_FUNCTION_SUCCEEDED) + ret = SUCCESS; - return SUCCESS; +out: + mempool_free(cmd, virtscsi_cmd_pool); + return ret; } static int virtscsi_device_reset(struct scsi_cmnd *sc) |