[PATCH 4.9 041/175] libata: fix ata_host_start()

[Greg Kroah-Hartman]

From: Damien Le Moal <damien.lemoal@xxxxxxx>

[ Upstream commit 355a8031dc174450ccad2a61c513ad7222d87a97 ]

The loop on entry of ata_host_start() may not initialize host->ops to a
non NULL value. The test on the host_stop field of host->ops must then
be preceded by a check that host->ops is not NULL.

Reported-by: kernel test robot <lkp@xxxxxxxxx>
Signed-off-by: Damien Le Moal <damien.lemoal@xxxxxxx>
Reviewed-by: Hannes Reinecke <hare@xxxxxxx>
Link: https://lore.kernel.org/r/20210816014456.2191776-3-damien.lemoal@xxxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/ata/libata-core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 228a4cfb0e7d..ea42840575ca 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -6213,7 +6213,7 @@ int ata_host_start(struct ata_host *host)
 			have_stop = 1;
 	}
 
-	if (host->ops->host_stop)
+	if (host->ops && host->ops->host_stop)
 		have_stop = 1;
 
 	if (have_stop) {
-- 
2.30.2