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Patch "USB: gadgetfs, dummy-hcd, net2280: fix locking for callbacks" has been added to the 4.9-stable tree

PATCH [email protected] 1 participant 1 message Jun 18, 2017

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

USB: gadgetfs, dummy-hcd, net2280: fix locking for callbacks

to the 4.9-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-gadgetfs-dummy-hcd-net2280-fix-locking-for-callbacks.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From f16443a034c7aa359ddf6f0f9bc40d01ca31faea Mon Sep 17 00:00:00 2001

From: Alan Stern <[email protected]>
Date: Tue, 13 Jun 2017 15:23:42 -0400
Subject: USB: gadgetfs, dummy-hcd, net2280: fix locking for callbacks

From: Alan Stern <[email protected]>

commit f16443a034c7aa359ddf6f0f9bc40d01ca31faea upstream.

Using the syzkaller kernel fuzzer, Andrey Konovalov generated the following error in gadgetfs:

Quoted 101 lines
BUG: KASAN: use-after-free in __lock_acquire+0x3069/0x3690
kernel/locking/lockdep.c:3246
Read of size 8 at addr ffff88003a2bdaf8 by task kworker/3:1/903

CPU: 3 PID: 903 Comm: kworker/3:1 Not tainted 4.12.0-rc4+ #35
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
Workqueue: usb_hub_wq hub_event
Call Trace:
 __dump_stack lib/dump_stack.c:16 [inline]
 dump_stack+0x292/0x395 lib/dump_stack.c:52
 print_address_description+0x78/0x280 mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report+0x230/0x340 mm/kasan/report.c:408
 __asan_report_load8_noabort+0x19/0x20 mm/kasan/report.c:429
 __lock_acquire+0x3069/0x3690 kernel/locking/lockdep.c:3246
 lock_acquire+0x22d/0x560 kernel/locking/lockdep.c:3855
 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
 _raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:151
 spin_lock include/linux/spinlock.h:299 [inline]
 gadgetfs_suspend+0x89/0x130 drivers/usb/gadget/legacy/inode.c:1682
 set_link_state+0x88e/0xae0 drivers/usb/gadget/udc/dummy_hcd.c:455
 dummy_hub_control+0xd7e/0x1fb0 drivers/usb/gadget/udc/dummy_hcd.c:2074
 rh_call_control drivers/usb/core/hcd.c:689 [inline]
 rh_urb_enqueue drivers/usb/core/hcd.c:846 [inline]
 usb_hcd_submit_urb+0x92f/0x20b0 drivers/usb/core/hcd.c:1650
 usb_submit_urb+0x8b2/0x12c0 drivers/usb/core/urb.c:542
 usb_start_wait_urb+0x148/0x5b0 drivers/usb/core/message.c:56
 usb_internal_control_msg drivers/usb/core/message.c:100 [inline]
 usb_control_msg+0x341/0x4d0 drivers/usb/core/message.c:151
 usb_clear_port_feature+0x74/0xa0 drivers/usb/core/hub.c:412
 hub_port_disable+0x123/0x510 drivers/usb/core/hub.c:4177
 hub_port_init+0x1ed/0x2940 drivers/usb/core/hub.c:4648
 hub_port_connect drivers/usb/core/hub.c:4826 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:4999 [inline]
 port_event drivers/usb/core/hub.c:5105 [inline]
 hub_event+0x1ae1/0x3d40 drivers/usb/core/hub.c:5185
 process_one_work+0xc08/0x1bd0 kernel/workqueue.c:2097
 process_scheduled_works kernel/workqueue.c:2157 [inline]
 worker_thread+0xb2b/0x1860 kernel/workqueue.c:2233
 kthread+0x363/0x440 kernel/kthread.c:231
 ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:424

Allocated by task 9958:
 save_stack_trace+0x1b/0x20 arch/x86/kernel/stacktrace.c:59
 save_stack+0x43/0xd0 mm/kasan/kasan.c:513
 set_track mm/kasan/kasan.c:525 [inline]
 kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:617
 kmem_cache_alloc_trace+0x87/0x280 mm/slub.c:2745
 kmalloc include/linux/slab.h:492 [inline]
 kzalloc include/linux/slab.h:665 [inline]
 dev_new drivers/usb/gadget/legacy/inode.c:170 [inline]
 gadgetfs_fill_super+0x24f/0x540 drivers/usb/gadget/legacy/inode.c:1993
 mount_single+0xf6/0x160 fs/super.c:1192
 gadgetfs_mount+0x31/0x40 drivers/usb/gadget/legacy/inode.c:2019
 mount_fs+0x9c/0x2d0 fs/super.c:1223
 vfs_kern_mount.part.25+0xcb/0x490 fs/namespace.c:976
 vfs_kern_mount fs/namespace.c:2509 [inline]
 do_new_mount fs/namespace.c:2512 [inline]
 do_mount+0x41b/0x2d90 fs/namespace.c:2834
 SYSC_mount fs/namespace.c:3050 [inline]
 SyS_mount+0xb0/0x120 fs/namespace.c:3027
 entry_SYSCALL_64_fastpath+0x1f/0xbe

Freed by task 9960:
 save_stack_trace+0x1b/0x20 arch/x86/kernel/stacktrace.c:59
 save_stack+0x43/0xd0 mm/kasan/kasan.c:513
 set_track mm/kasan/kasan.c:525 [inline]
 kasan_slab_free+0x72/0xc0 mm/kasan/kasan.c:590
 slab_free_hook mm/slub.c:1357 [inline]
 slab_free_freelist_hook mm/slub.c:1379 [inline]
 slab_free mm/slub.c:2961 [inline]
 kfree+0xed/0x2b0 mm/slub.c:3882
 put_dev+0x124/0x160 drivers/usb/gadget/legacy/inode.c:163
 gadgetfs_kill_sb+0x33/0x60 drivers/usb/gadget/legacy/inode.c:2027
 deactivate_locked_super+0x8d/0xd0 fs/super.c:309
 deactivate_super+0x21e/0x310 fs/super.c:340
 cleanup_mnt+0xb7/0x150 fs/namespace.c:1112
 __cleanup_mnt+0x1b/0x20 fs/namespace.c:1119
 task_work_run+0x1a0/0x280 kernel/task_work.c:116
 exit_task_work include/linux/task_work.h:21 [inline]
 do_exit+0x18a8/0x2820 kernel/exit.c:878
 do_group_exit+0x14e/0x420 kernel/exit.c:982
 get_signal+0x784/0x1780 kernel/signal.c:2318
 do_signal+0xd7/0x2130 arch/x86/kernel/signal.c:808
 exit_to_usermode_loop+0x1ac/0x240 arch/x86/entry/common.c:157
 prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline]
 syscall_return_slowpath+0x3ba/0x410 arch/x86/entry/common.c:263
 entry_SYSCALL_64_fastpath+0xbc/0xbe

The buggy address belongs to the object at ffff88003a2bdae0
 which belongs to the cache kmalloc-1024 of size 1024
The buggy address is located 24 bytes inside of
 1024-byte region [ffff88003a2bdae0, ffff88003a2bdee0)
The buggy address belongs to the page:
page:ffffea0000e8ae00 count:1 mapcount:0 mapping:          (null)
index:0x0 compound_mapcount: 0
flags: 0x100000000008100(slab|head)
raw: 0100000000008100 0000000000000000 0000000000000000 0000000100170017
raw: ffffea0000ed3020 ffffea0000f5f820 ffff88003e80efc0 0000000000000000
page dumped because: kasan: bad access detected
Quoted 8 lines
Memory state around the buggy address:
 ffff88003a2bd980: fb fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88003a2bda00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88003a2bda80: fc fc fc fc fc fc fc fc fc fc fc fc fb fb fb fb
                                                                ^
 ffff88003a2bdb00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88003a2bdb80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

What this means is that the gadgetfs_suspend() routine was trying to access dev->lock after it had been deallocated. The root cause is a race in the dummy_hcd driver; the dummy_udc_stop() routine can race with the rest of the driver because it contains no locking. And even when proper locking is added, it can still race with the set_link_state() function because that function incorrectly drops the private spinlock before invoking any gadget driver callbacks.

The result of this race, as seen above, is that set_link_state() can invoke a callback in gadgetfs even after gadgetfs has been unbound from dummy_hcd's UDC and its private data structures have been deallocated.

include/linux/usb/gadget.h documents that the ->reset, ->disconnect, ->suspend, and ->resume callbacks may be invoked in interrupt context. In general this is necessary, to prevent races with gadget driver removal. This patch fixes dummy_hcd to retain the spinlock across these calls, and it adds a spinlock acquisition to dummy_udc_stop() to prevent the race.

The net2280 driver makes the same mistake of dropping the private spinlock for its ->disconnect and ->reset callback invocations. The patch fixes it too.

Lastly, since gadgetfs_suspend() may be invoked in interrupt context, it cannot assume that interrupts are enabled when it runs. It must use spin_lock_irqsave() instead of spin_lock_irq(). The patch fixes that bug as well.

Signed-off-by Alan Stern <[email protected]>
Reported-and-tested-by Andrey Konovalov <[email protected]>
Acked-by Felipe Balbi <[email protected]>
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 drivers/usb/gadget/legacy/inode.c  |    5 +++--
 drivers/usb/gadget/udc/dummy_hcd.c |   13 ++++---------
 drivers/usb/gadget/udc/net2280.c   |    9 +--------
 3 files changed, 8 insertions(+), 19 deletions(-)
drivers/usb/gadget/legacy/inode.c +3 -2
@@ -1679,9 +1679,10 @@ static void
 gadgetfs_suspend (struct usb_gadget *gadget)
 {
 	struct dev_data		*dev = get_gadget_data (gadget);
+	unsigned long		flags;
 
 	INFO (dev, "suspended from state %d\n", dev->state);
-	spin_lock (&dev->lock);
+	spin_lock_irqsave(&dev->lock, flags);
 	switch (dev->state) {
 	case STATE_DEV_SETUP:		// VERY odd... host died??
 	case STATE_DEV_CONNECTED:

@@ -1692,7 +1693,7 @@ gadgetfs_suspend (struct usb_gadget *gad
 	default:
 		break;
 	}
-	spin_unlock (&dev->lock);
+	spin_unlock_irqrestore(&dev->lock, flags);
 }
 
 static struct usb_gadget_driver gadgetfs_driver = {
drivers/usb/gadget/udc/dummy_hcd.c +4 -9
@@ -442,23 +442,16 @@ static void set_link_state(struct dummy_
 		/* Report reset and disconnect events to the driver */
 		if (dum->driver && (disconnect || reset)) {
 			stop_activity(dum);
-			spin_unlock(&dum->lock);
 			if (reset)
 				usb_gadget_udc_reset(&dum->gadget, dum->driver);
 			else
 				dum->driver->disconnect(&dum->gadget);
-			spin_lock(&dum->lock);
 		}
 	} else if (dum_hcd->active != dum_hcd->old_active) {
-		if (dum_hcd->old_active && dum->driver->suspend) {
-			spin_unlock(&dum->lock);
+		if (dum_hcd->old_active && dum->driver->suspend)
 			dum->driver->suspend(&dum->gadget);
-			spin_lock(&dum->lock);
-		} else if (!dum_hcd->old_active &&  dum->driver->resume) {
-			spin_unlock(&dum->lock);
+		else if (!dum_hcd->old_active &&  dum->driver->resume)
 			dum->driver->resume(&dum->gadget);
-			spin_lock(&dum->lock);
-		}
 	}
 
 	dum_hcd->old_status = dum_hcd->port_status;

@@ -983,7 +976,9 @@ static int dummy_udc_stop(struct usb_gad
 	struct dummy_hcd	*dum_hcd = gadget_to_dummy_hcd(g);
 	struct dummy		*dum = dum_hcd->dum;
 
+	spin_lock_irq(&dum->lock);
 	dum->driver = NULL;
+	spin_unlock_irq(&dum->lock);
 
 	return 0;
 }
drivers/usb/gadget/udc/net2280.c +1 -8
@@ -2469,11 +2469,8 @@ static void stop_activity(struct net2280
 		nuke(&dev->ep[i]);
 
 	/* report disconnect; the driver is already quiesced */
-	if (driver) {
-		spin_unlock(&dev->lock);
+	if (driver)
 		driver->disconnect(&dev->gadget);
-		spin_lock(&dev->lock);
-	}
 
 	usb_reinit(dev);
 }

@@ -3347,8 +3344,6 @@ next_endpoints:
 		BIT(PCI_RETRY_ABORT_INTERRUPT))
 
 static void handle_stat1_irqs(struct net2280 *dev, u32 stat)
-__releases(dev->lock)
-__acquires(dev->lock)
 {
 	struct net2280_ep	*ep;
 	u32			tmp, num, mask, scratch;

@@ -3389,14 +3384,12 @@ __acquires(dev->lock)
 			if (disconnect || reset) {
 				stop_activity(dev, dev->driver);
 				ep0_start(dev);
-				spin_unlock(&dev->lock);
 				if (reset)
 					usb_gadget_udc_reset
 						(&dev->gadget, dev->driver);
 				else
 					(dev->driver->disconnect)
 						(&dev->gadget);
-				spin_lock(&dev->lock);
 				return;
 			}
 		}

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/usb-gadgetfs-dummy-hcd-net2280-fix-locking-for-callbacks.patch queue-4.9/usb-core-fix-potential-memory-leak-in-error-path-during-hcd-creation.patch queue-4.9/usb-gadget-dummy_hcd-fix-hub-descriptor-removable-fields.patch queue-4.9/usb-hub-fix-ss-max-number-of-ports.patch queue-4.9/usb-gadget-fix-gpf-in-gadgetfs.patch