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ACPI / device_sysfs: Avoid OF modalias creation for removed device

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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: 8765c5ba19 ("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>
This commit is contained in:
Andy Shevchenko 2019-03-11 18:41:03 +02:00 committed by Rafael J. Wysocki
parent d276709ce6
commit f16eb8a4b0
1 changed files with 5 additions and 1 deletions
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6
drivers/acpi/device_sysfs.c
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@ -202,11 +202,15 @@ static int create_of_modalias(struct acpi_device *acpi_dev, char *modalias,
{
struct acpi_buffer buf = { ACPI_ALLOCATE_BUFFER };
const union acpi_object *of_compatible, *obj;
acpi_status status;
int len, count;
int i, nval;
char *c;
acpi_get_name(acpi_dev->handle, ACPI_SINGLE_NAME, &buf);
status = acpi_get_name(acpi_dev->handle, ACPI_SINGLE_NAME, &buf);
if (ACPI_FAILURE(status))
return -ENODEV;
/* DT strings are all in lower case */
for (c = buf.pointer; *c != '\0'; c++)
*c = tolower(*c);