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authorPaolo Bonzini <pbonzini@redhat.com>2012-05-04 12:32:04 +0200
committerJames Bottomley <JBottomley@Parallels.com>2012-05-10 08:27:06 +0100
commite4594bb50518eb89c447be97dabd5bd99f405d71 (patch)
treef4e8d81b2b30cb8ab53207382c2841983954b833 /drivers
parent3c8d9a957d0ae62c2815393a781ab7ff4d5205e7 (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>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/scsi/virtio_scsi.c24
1 files changed, 13 insertions, 11 deletions
diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
index efccd72c4a3e..1b3843117268 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 = &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)