From:   "Rafael J. Wysocki" <rjw@rjwysocki.net>
To:     Linux ACPI <linux-acpi@vger.kernel.org>
Cc:     LKML <linux-kernel@vger.kernel.org>,
        Bob Moore <robert.moore@intel.com>
Subject: [PATCH 08/19] ACPICA: Utilities: Avoid deleting the same object twice in a row
Date:   Wed, 22 Dec 2021 17:29:45 +0100
Message-ID: <3407207.iIbC2pHGDl@kreacher>
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References: <11889746.O9o76ZdvQC@kreacher>
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From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>

ACPICA commit c11af67d8f7e3d381068ce7771322f2b5324d687

If original_count is 0 in acpi_ut_update_ref_count (),
acpi_ut_delete_internal_obj () is invoked for the target object, which is
incorrect, because that object has been deleted once already and the
memory allocated to store it may have been reclaimed and allocated
for a different purpose by the host OS.  Moreover, a confusing debug
message following the "Reference Count is already zero, cannot
decrement" warning is printed in that case.

To fix this issue, make acpi_ut_update_ref_count () return after finding
that original_count is 0 and printing the above warning.

Link: https://github.com/acpica/acpica/commit/c11af67d
Link: https://github.com/acpica/acpica/pull/652
Reported-by: Mark Asselstine <mark.asselstine@windriver.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Bob Moore <robert.moore@intel.com>
---
 drivers/acpi/acpica/utdelete.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/acpi/acpica/utdelete.c b/drivers/acpi/acpica/utdelete.c
index e5ba9795ec69..8d7736d2d269 100644
--- a/drivers/acpi/acpica/utdelete.c
+++ b/drivers/acpi/acpica/utdelete.c
@@ -422,6 +422,7 @@ acpi_ut_update_ref_count(union acpi_operand_object *object, u32 action)
 			ACPI_WARNING((AE_INFO,
 				      "Obj %p, Reference Count is already zero, cannot decrement\n",
 				      object));
+			return;
 		}
 
 		ACPI_DEBUG_PRINT_RAW((ACPI_DB_ALLOCATIONS,
-- 
2.26.2