linux-kernel - [PATCH 4.19 026/361] ACPICA: AML Parser: fix parse loop to correctly skip erroneous extended opcodes

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Date:   Sun, 11 Nov 2018 14:16:13 -0800
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Erik Schmauss <erik.schmauss@...el.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
Subject: [PATCH 4.19 026/361] ACPICA: AML Parser: fix parse loop to correctly skip erroneous extended opcodes

4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Erik Schmauss <erik.schmauss@...el.com>

commit c64baa3a6fa207d112706bc5e7fd645cd8a8663f upstream.

AML opcodes come in two lengths: 1-byte opcodes and 2-byte, extended opcodes.
If an error occurs due to illegal opcodes during table load, the AML parser
needs to continue loading the table. In order to do this, it needs to skip
parsing of the offending opcode and operands associated with that opcode.

This change fixes the AML parse loop to correctly skip parsing of incorrect
extended opcodes. Previously, only the short opcodes were skipped correctly.

Signed-off-by: Erik Schmauss <erik.schmauss@...el.com>
Cc: All applicable <stable@...r.kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/acpi/acpica/psloop.c |   14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

--- a/drivers/acpi/acpica/psloop.c
+++ b/drivers/acpi/acpica/psloop.c
@@ -417,6 +417,7 @@ acpi_status acpi_ps_parse_loop(struct ac
 	union acpi_parse_object *op = NULL;	/* current op */
 	struct acpi_parse_state *parser_state;
 	u8 *aml_op_start = NULL;
+	u8 opcode_length;

 	ACPI_FUNCTION_TRACE_PTR(ps_parse_loop, walk_state);

@@ -540,8 +541,19 @@ acpi_status acpi_ps_parse_loop(struct ac
 						    "Skip parsing opcode %s",
 						    acpi_ps_get_opcode_name
 						    (walk_state->opcode)));
+
+					/*
+					 * Determine the opcode length before skipping the opcode.
+					 * An opcode can be 1 byte or 2 bytes in length.
+					 */
+					opcode_length = 1;
+					if ((walk_state->opcode & 0xFF00) ==
+					    AML_EXTENDED_OPCODE) {
+						opcode_length = 2;
+					}
 					walk_state->parser_state.aml =
-					    walk_state->aml + 1;
+					    walk_state->aml + opcode_length;
+
 					walk_state->parser_state.aml =
 					    acpi_ps_get_next_package_end
 					    (&walk_state->parser_state);