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Subject[PATCH 4.12 070/196] usb: storage: return on error to avoid a null pointer dereference
Date
4.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Colin Ian King <colin.king@canonical.com>

commit 446230f52a5bef593554510302465eabab45a372 upstream.

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
check.

Thanks to Alan Stern for pointing out that srb->result needs setting
to DID_ERROR << 16

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

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/usb/storage/isd200.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

--- a/drivers/usb/storage/isd200.c
+++ b/drivers/usb/storage/isd200.c
@@ -1529,8 +1529,11 @@ static void isd200_ata_command(struct sc

/* Make sure driver was initialized */

- if (us->extra == NULL)
+ if (us->extra == NULL) {
usb_stor_dbg(us, "ERROR Driver not initialized\n");
+ srb->result = DID_ERROR << 16;
+ return;
+ }

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

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