Patch "usb: storage: return on error to avoid a null pointer dereference" has been added to the 4.12-stable tree

Patch "usb: storage: return on error to avoid a null pointer dereference" has been added to the 4.12-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

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

to the 4.12-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     usb-storage-return-on-error-to-avoid-a-null-pointer-dereference.patch
and it can be found in the queue-4.12 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 446230f52a5bef593554510302465eabab45a372 Mon Sep 17 00:00:00 2001
From: Colin Ian King <colin.king@canonical.com>
Date: Thu, 6 Jul 2017 16:06:32 +0100
Subject: usb: storage: return on error to avoid a null pointer dereference

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 */


Patches currently in stable-queue which might be from colin.king@canonical.com are

queue-4.12/usb-storage-return-on-error-to-avoid-a-null-pointer-dereference.patch