[PATCH AUTOSEL 5.4 9/9] ACPI: fix NULL pointer dereference

Sasha Levin
2021-07-27T13:30:28Z

From: Linus Torvalds <torvalds@linux-foundation.org>

[ Upstream commit fc68f42aa737dc15e7665a4101d4168aadb8e4c4 ]

Commit 71f642833284 ("ACPI: utils: Fix reference counting in
for_each_acpi_dev_match()") started doing "acpi_dev_put()" on a pointer
that was possibly NULL. That fails miserably, because that helper
inline function is not set up to handle that case.

Just make acpi_dev_put() silently accept a NULL pointer, rather than
calling down to put_device() with an invalid offset off that NULL
pointer.

Link: https://lore.kernel.org/lkml/a607c149-6bf6-0fd0-0e31-100378504da2@kernel.dk/
Reported-and-tested-by: Jens Axboe <axboe@kernel.dk>
Tested-by: Daniel Scally <djrscally@gmail.com>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/acpi/acpi_bus.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index 4d67a67964fa..1e5ae3b01eb2 100644
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -681,7 +681,8 @@ acpi_dev_get_first_match_dev(const char *hid, const char *uid, s64 hrv);

static inline void acpi_dev_put(struct acpi_device *adev)
{
- put_device(&adev->dev);
+ if (adev)
+ put_device(&adev->dev);
}
#else /* CONFIG_ACPI */

--
2.30.2