libata: add refcounting to ata_host
After commit 9a6d6a2ddabb ("ata: make ata port as parent device of scsi
host") manual driver unbind/remove causes use-after-free.
Unbind unconditionally invokes devres_release_all() which calls
ata_host_release() and frees ata_host/ata_port memory while it is still
being referenced as a parent of SCSI host. When SCSI host is finally
released scsi_host_dev_release() calls put_device(parent) and accesses
freed ata_port memory.
Add reference counting to make sure that ata_host lives long enough.
Bug report: https://lkml.org/lkml/2017/11/1/945
Fixes: 9a6d6a2ddabb ("ata: make ata port as parent device of scsi host")
Cc: Tejun Heo <tj@kernel.org>
Cc: Lin Ming <minggr@gmail.com>
Cc: linux-ide@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Taras Kondratiuk <takondra@cisco.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
diff --git a/drivers/ata/libata.h b/drivers/ata/libata.h
index f953cb4..9e21c49 100644
--- a/drivers/ata/libata.h
+++ b/drivers/ata/libata.h
@@ -100,6 +100,8 @@ extern int ata_port_probe(struct ata_port *ap);
extern void __ata_port_probe(struct ata_port *ap);
extern unsigned int ata_read_log_page(struct ata_device *dev, u8 log,
u8 page, void *buf, unsigned int sectors);
+extern void ata_host_get(struct ata_host *host);
+extern void ata_host_put(struct ata_host *host);
#define to_ata_port(d) container_of(d, struct ata_port, tdev)