[PATCH] usb: storage: return on error to avoid a null pointer dereference

From: Colin King
Date: Thu Jul 06 2017 - 06:06:57 EST

From: Colin Ian King <colin.king@xxxxxxxxxxxxx>

When us->extra is null the driver is not initialized, however, a
later call to osd200_scsi_to_ata is made that dereferences
us->extra, causing a null pointer dereference. The code
currently detects and reports that the driver is not initialized;
add a return to avoid the subsequent dereference issue in this

Detected by CoverityScan, CID#100308 ("Dereference after null check")

Signed-off-by: Colin Ian King <colin.king@xxxxxxxxxxxxx>
drivers/usb/storage/isd200.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/storage/isd200.c b/drivers/usb/storage/isd200.c
index fba4005dd737..174ad60679e7 100644
--- a/drivers/usb/storage/isd200.c
+++ b/drivers/usb/storage/isd200.c
@@ -1529,8 +1529,10 @@ static void isd200_ata_command(struct scsi_cmnd *srb, struct us_data *us)

/* Make sure driver was initialized */

- if (us->extra == NULL)
+ if (us->extra == NULL) {
usb_stor_dbg(us, "ERROR Driver not initialized\n");
+ return;
+ }

scsi_set_resid(srb, 0);
/* scsi_bufflen might change in protocol translation to ata */