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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <20170706100635.16610-1-colin.king@canonical.com>
Date:   Thu,  6 Jul 2017 11:06:35 +0100
From:   Colin King <colin.king@...onical.com>
To:     Alan Stern <stern@...land.harvard.edu>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org, usb-storage@...ts.one-eyed-alien.net
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] usb: storage: return on error to avoid a null pointer dereference

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

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.

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

Signed-off-by: Colin Ian King <colin.king@...onical.com>
---
 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 */
-- 
2.11.0