[PATCH 3.18 27/60] usb: storage: return on error to avoid a null pointer dereference

From	Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Newsgroups	linux.kernel
Subject	[PATCH 3.18 27/60] usb: storage: return on error to avoid a null pointer dereference
Date	2017-07-25 23:40 +0200
Message-ID	<u7fIB-8eE-1@gated-at.bofh.it> (permalink)
References	<u7dx7-6OD-3@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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3.18-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
@@ -1522,8 +1522,11 @@ 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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[PATCH 3.18 27/60] usb: storage: return on error to avoid a null pointer dereference Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-25 23:40 +0200

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