ACPI / device_sysfs: Avoid OF modalias creation for removed device
If SSDT overlay is loaded via ConfigFS and then unloaded the device,
we would like to have OF modalias for, already gone. Thus, acpi_get_name()
returns no allocated buffer for such case and kernel crashes afterwards:
ACPI: Host-directed Dynamic ACPI Table Unload
ads7950 spi-PRP0001:00: Dropping the link to regulator.0
BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
#PF error: [normal kernel read fault]
PGD 80000000070d6067 P4D 80000000070d6067 PUD 70d0067 PMD 0
Oops: 0000 [#1] SMP PTI
CPU: 0 PID: 40 Comm: kworker/u4:2 Not tainted 5.0.0+ #96
Hardware name: Intel Corporation Merrifield/BODEGA BAY, BIOS 542 2015.01.21:18.19.48
Workqueue: kacpi_hotplug acpi_device_del_work_fn
RIP: 0010:create_of_modalias.isra.1+0x4c/0x150
Code: 00 00 48 89 44 24 18 31 c0 48 8d 54 24 08 48 c7 44 24 10 00 00 00 00 48 c7 44 24 08 ff ff ff ff e8 7a b0 03 00 48 8b 4c 24 10 <0f> b6 01 84 c0 74 27 48 c7 c7 00 09 f4 a5 0f b6 f0 8d 50 20 f6 04
RSP: 0000:ffffa51040297c10 EFLAGS: 00010246
RAX: 0000000000001001 RBX: 0000000000000785 RCX: 0000000000000000
RDX: 0000000000001001 RSI: 0000000000000286 RDI: ffffa2163dc042e0
RBP: ffffa216062b1196 R08: 0000000000001001 R09: ffffa21639873000
R10: ffffffffa606761d R11: 0000000000000001 R12: ffffa21639873218
R13: ffffa2163deb5060 R14: ffffa216063d1010 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffffa2163e000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000007114000 CR4: 00000000001006f0
Call Trace:
__acpi_device_uevent_modalias+0xb0/0x100
spi_uevent+0xd/0x40
...
In order to fix above let create_of_modalias() check the status returned
by acpi_get_name() and bail out in case of failure.
Fixes: 8765c5ba1949 ("ACPI / scan: Rework modalias creation when "compatible" is present")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=201381
Reported-by: Ferry Toth <fntoth@gmail.com>
Tested-by: Ferry Toth<fntoth@gmail.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: 4.1+ <stable@vger.kernel.org> # 4.1+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
1 file changed
