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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Daniel Scally <djrscally@gmail.com>,
        Andy Shevchenko <andy.shevchenko@gmail.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Sasha Levin <sashal@kernel.org>, Jens Axboe <axboe@kernel.dk>
Subject: [PATCH 5.10 19/30] ACPI: fix NULL pointer dereference
Date:   Fri,  6 Aug 2021 10:16:57 +0200
Message-Id: <20210806081113.780004075@linuxfoundation.org>
In-Reply-To: <20210806081113.126861800@linuxfoundation.org>
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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 37dac195adbb..6ad3b89a8a2e 100644
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -689,7 +689,8 @@ 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