From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Sat, 24 Jul 2021 22:25:54 +0000 (-0700)
Subject: ACPI: fix NULL pointer dereference
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=fc68f42aa737;p=linux.git

ACPI: fix NULL pointer dereference

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>
---

diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index b9d434a936320..13d93371790ec 100644
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -720,7 +720,8 @@ static inline struct acpi_device *acpi_dev_get(struct acpi_device *adev)
 
 static inline void acpi_dev_put(struct acpi_device *adev)
 {
-	put_device(&adev->dev);
+	if (adev)
+		put_device(&adev->dev);
 }
 
 struct acpi_device *acpi_bus_get_acpi_device(acpi_handle handle);