Received-SPF: softfail (google.com: domain of transitioning linux-kernel-owner@vger.kernel.org does not designate 23.128.96.19 as permitted sender) client-ip=23.128.96.19;
From:   Pavel Skripkin <paskripkin@gmail.com>
To:     krzysztof.kozlowski@canonical.com, sameo@linux.intel.com,
        thierry.escande@linux.intel.com
Cc:     netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        Pavel Skripkin <paskripkin@gmail.com>,
        syzbot+16bcb127fb73baeecb14@syzkaller.appspotmail.com
Subject: [PATCH] NFC: port100: fix use-after-free in port100_send_complete
Date:   Tue,  8 Mar 2022 21:50:07 +0300
Message-Id: <20220308185007.6987-1-paskripkin@gmail.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

Syzbot reported UAF in port100_send_complete(). The root case is in
missing usb_kill_urb() calls on error handling path of ->probe function.

port100_send_complete() accesses devm allocated memory which will be
freed on probe failure. We should kill this urbs before returning an
error from probe function to prevent reported use-after-free

Fail log:

BUG: KASAN: use-after-free in port100_send_complete+0x16e/0x1a0 drivers/nfc/port100.c:935
Read of size 1 at addr ffff88801bb59540 by task ksoftirqd/2/26
...
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 print_address_description.constprop.0.cold+0x8d/0x303 mm/kasan/report.c:255
 __kasan_report mm/kasan/report.c:442 [inline]
 kasan_report.cold+0x83/0xdf mm/kasan/report.c:459
 port100_send_complete+0x16e/0x1a0 drivers/nfc/port100.c:935
 __usb_hcd_giveback_urb+0x2b0/0x5c0 drivers/usb/core/hcd.c:1670

...

Allocated by task 1255:
 kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
 kasan_set_track mm/kasan/common.c:45 [inline]
 set_alloc_info mm/kasan/common.c:436 [inline]
 ____kasan_kmalloc mm/kasan/common.c:515 [inline]
 ____kasan_kmalloc mm/kasan/common.c:474 [inline]
 __kasan_kmalloc+0xa6/0xd0 mm/kasan/common.c:524
 alloc_dr drivers/base/devres.c:116 [inline]
 devm_kmalloc+0x96/0x1d0 drivers/base/devres.c:823
 devm_kzalloc include/linux/device.h:209 [inline]
 port100_probe+0x8a/0x1320 drivers/nfc/port100.c:1502

Freed by task 1255:
 kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
 kasan_set_track+0x21/0x30 mm/kasan/common.c:45
 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:370
 ____kasan_slab_free mm/kasan/common.c:366 [inline]
 ____kasan_slab_free+0xff/0x140 mm/kasan/common.c:328
 kasan_slab_free include/linux/kasan.h:236 [inline]
 __cache_free mm/slab.c:3437 [inline]
 kfree+0xf8/0x2b0 mm/slab.c:3794
 release_nodes+0x112/0x1a0 drivers/base/devres.c:501
 devres_release_all+0x114/0x190 drivers/base/devres.c:530
 really_probe+0x626/0xcc0 drivers/base/dd.c:670

Reported-and-tested-by: syzbot+16bcb127fb73baeecb14@syzkaller.appspotmail.com
Fixes: 0347a6ab300a ("NFC: port100: Commands mechanism implementation")
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
---
 drivers/nfc/port100.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/nfc/port100.c b/drivers/nfc/port100.c
index d7db1a0e6be1..00d8ea6dcb5d 100644
--- a/drivers/nfc/port100.c
+++ b/drivers/nfc/port100.c
@@ -1612,7 +1612,9 @@ static int port100_probe(struct usb_interface *interface,
 	nfc_digital_free_device(dev->nfc_digital_dev);
 
 error:
+	usb_kill_urb(dev->in_urb);
 	usb_free_urb(dev->in_urb);
+	usb_kill_urb(dev->out_urb);
 	usb_free_urb(dev->out_urb);
 	usb_put_dev(dev->udev);
 
-- 
2.35.1