[BUG] iio: gyro: mpu3050: use-after-free via trigger left on iio_trigger_list after unbind

[Dingisoul <dingiso.kernel@gmail.com>]

Hi Kernel Maintainers,

I hit the following report while testing current upstream kernel:

KASAN: slab-use-after-free in mpu3050_drdy_trigger_set_state

on commit: a90ee4305c4a (2026-10-07)

Root cause: mpu3050_trigger_probe() registers the data-ready trigger with
the non-devm iio_trigger_register(), with drvdata pointing at indio_dev:

    static int mpu3050_trigger_probe(struct iio_dev *indio_dev, int irq)
    {
        ...
        mpu3050->trig->dev.parent = dev;
        mpu3050->trig->ops = &mpu3050_trigger_ops;
        iio_trigger_set_drvdata(mpu3050->trig, indio_dev);

        ret = iio_trigger_register(mpu3050->trig);  /* device_add() pins trig; no unregister on remove */
        if (ret)
            goto err_iio_trigger;

        indio_dev->trig = iio_trigger_get(mpu3050->trig);

        return 0;
    }

mpu3050_common_remove() tears down everything else, but never calls
iio_trigger_unregister() on mpu3050->trig:

    void mpu3050_common_remove(struct device *dev)
    {
        struct iio_dev *indio_dev = dev_get_drvdata(dev);
        struct mpu3050 *mpu3050 = iio_priv(indio_dev);

        iio_device_unregister(indio_dev);  /* devm frees indio_dev's storage once this returns */
        pm_runtime_get_sync(dev);
        pm_runtime_put_noidle(dev);
        pm_runtime_disable(dev);
        if (mpu3050->irq)
            free_irq(mpu3050->irq, mpu3050->trig);
        iio_triggered_buffer_cleanup(indio_dev);
        mpu3050_power_down(mpu3050);
        /* trig is never unregistered: still on the global iio_trigger_list */
    }

So after unbind, the trigger is still alive and discoverable by name on
the global trigger list, with drvdata still pointing at the now-freed
indio_dev. Any other IIO device with a triggered buffer can select it by
name via trigger/current_trigger and enable its buffer, which reaches
the leaked trigger's ->set_trigger_state() op:

    static int mpu3050_drdy_trigger_set_state(struct iio_trigger *trig,
                                              bool enable)
    {
        struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
        struct mpu3050 *mpu3050 = iio_priv(indio_dev);  /* indio_dev is freed -- UAF read */
        ...

The reproducer and .config files are here.
https://gist.github.com/dingiso/985aa3eb2786b62f80e2e6780e9af090

I'm happy to test debug patches or provide additional information.

[   24.039594][ T8117] BUG: KASAN: slab-use-after-free in mpu3050_drdy_trigger_set_state (./include/linux/iio/iio.h:980 drivers/iio/gyro/mpu3050-core.c:957)
[   24.039630][ T8117] Read of size 8 at addr ffff888030621388 by task repro/8117
[   24.039634][ T8117] 
[   24.039644][ T8117] Tainted: [E]=UNSIGNED_MODULE
[   24.039645][ T8117] Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
[   24.039648][ T8117] Call Trace:
[   24.039650][ T8117]  <TASK>
[   24.039651][ T8117]  dump_stack_lvl (lib/dump_stack.c:94 lib/dump_stack.c:120)
[   24.039663][ T8117]  print_report (mm/kasan/report.c:378 mm/kasan/report.c:482)
[   24.039682][ T8117]  kasan_report (mm/kasan/report.c:595)
[   24.039690][ T8117]  mpu3050_drdy_trigger_set_state (./include/linux/iio/iio.h:980 drivers/iio/gyro/mpu3050-core.c:957)
[   24.039709][ T8117]  iio_trigger_attach_poll_func (drivers/iio/industrialio-trigger.c:308)
[   24.039715][ T8117]  __iio_update_buffers (drivers/iio/industrialio-buffer.c:1207 drivers/iio/industrialio-buffer.c:1324)
[   24.039747][ T8117]  enable_store (drivers/iio/industrialio-buffer.c:1414)
[   24.039765][ T8117]  kernfs_fop_write_iter (fs/kernfs/file.c:345)
[   24.039769][ T8117]  vfs_write (fs/read_write.c:595 fs/read_write.c:687)
[   24.039786][ T8117]  ksys_write (fs/read_write.c:739)
[   24.039795][ T8117]  do_syscall_64 (arch/x86/entry/syscall_64.c:61 arch/x86/entry/syscall_64.c:84)
[   24.039799][ T8117]  entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)
[   24.039803][ T8117] RIP: 0033:0x7fe293245473
[   24.039807][ T8117] Code: 8b 15 21 2a 0e 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b7 0f 1f 00 64 8b 04 25 18 00 00 00 85 c0 75 14 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 55 c3 0f 1f 40 00 48 83 ec 28 48 89 54 24 18
All code
========
   0:	8b 15 21 2a 0e 00    	mov    0xe2a21(%rip),%edx        # 0xe2a27
   6:	f7 d8                	neg    %eax
   8:	64 89 02             	mov    %eax,%fs:(%rdx)
   b:	48 c7 c0 ff ff ff ff 	mov    $0xffffffffffffffff,%rax
  12:	eb b7                	jmp    0xffffffffffffffcb
  14:	0f 1f 00             	nopl   (%rax)
  17:	64 8b 04 25 18 00 00 	mov    %fs:0x18,%eax
  1e:	00 
  1f:	85 c0                	test   %eax,%eax
  21:	75 14                	jne    0x37
  23:	b8 01 00 00 00       	mov    $0x1,%eax
  28:	0f 05                	syscall
  2a:*	48 3d 00 f0 ff ff    	cmp    $0xfffffffffffff000,%rax		<-- trapping instruction
  30:	77 55                	ja     0x87
  32:	c3                   	ret
  33:	0f 1f 40 00          	nopl   0x0(%rax)
  37:	48 83 ec 28          	sub    $0x28,%rsp
  3b:	48 89 54 24 18       	mov    %rdx,0x18(%rsp)

Code starting with the faulting instruction
===========================================
   0:	48 3d 00 f0 ff ff    	cmp    $0xfffffffffffff000,%rax
   6:	77 55                	ja     0x5d
   8:	c3                   	ret
   9:	0f 1f 40 00          	nopl   0x0(%rax)
   d:	48 83 ec 28          	sub    $0x28,%rsp
  11:	48 89 54 24 18       	mov    %rdx,0x18(%rsp)
[   24.039810][ T8117] RSP: 002b:00007fff7856e628 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
[   24.039815][ T8117] RAX: ffffffffffffffda RBX: 00007fff7856e6e0 RCX: 00007fe293245473
[   24.039818][ T8117] RDX: 0000000000000001 RSI: 000056386e819159 RDI: 0000000000000003
[   24.039820][ T8117] RBP: 0000000000000003 R08: 0000000000004000 R09: 00007fe2932e90c0
[   24.039822][ T8117] R10: 0000000000000000 R11: 0000000000000246 R12: 000056386e819159
[   24.039824][ T8117] R13: 00007fff7856ea60 R14: 00007fff7856ea60 R15: 0000563885c1635b
[   24.039827][ T8117]  </TASK>
[   24.039829][ T8117] 
[   24.039830][ T8117] Freed by task 8117:
[   24.039832][ T8117]  kasan_save_stack (mm/kasan/common.c:57)
[   24.039835][ T8117]  kasan_save_track (mm/kasan/common.c:78)
[   24.039838][ T8117]  kasan_save_free_info (mm/kasan/generic.c:584)
[   24.039841][ T8117]  __kasan_slab_free (mm/kasan/common.c:264 mm/kasan/common.c:296)
[   24.039844][ T8117]  kfree (./include/linux/kasan.h:235 mm/slub.c:2748 mm/slub.c:6509 mm/slub.c:6802)
[   24.039849][ T8117]  device_release (drivers/base/core.c:2645)
[   24.039854][ T8117]  kobject_put (lib/kobject.c:689 lib/kobject.c:720 ./include/linux/kref.h:65 lib/kobject.c:737)
[   24.039859][ T8117]  release_nodes (drivers/base/devres.c:546)
[   24.039862][ T8117]  devres_release_group (drivers/base/devres.c:739)
[   24.039865][ T8117]  i2c_device_remove (drivers/i2c/i2c-core-base.c:637)
[   24.039871][ T8117]  device_release_driver_internal (drivers/base/dd.c:1349 drivers/base/dd.c:1372)
[   24.039874][ T8117]  bus_remove_device (drivers/base/bus.c:664)
[   24.039878][ T8117]  device_del (drivers/base/core.c:3965)
[   24.039882][ T8117]  device_unregister (drivers/base/core.c:4006)
[   24.039885][ T8117]  delete_device_store (drivers/i2c/i2c-core-base.c:1369)
[   24.039889][ T8117]  kernfs_fop_write_iter (fs/kernfs/file.c:345)
[   24.039892][ T8117]  vfs_write (fs/read_write.c:595 fs/read_write.c:687)
[   24.039895][ T8117]  ksys_write (fs/read_write.c:739)
[   24.039899][ T8117]  do_syscall_64 (arch/x86/entry/syscall_64.c:61 arch/x86/entry/syscall_64.c:84)
[   24.039901][ T8117]  entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)
(Full KASAN report, including the trailing slab/page-owner and memory-state info after this point, is in the gist as kasan_report_full.txt. Lines starting with "?" above are stack-scanned frames, not reliable return addresses, and have been omitted here.)

Best,
Dingisoul