Commit 0de0e198 authored Apr 25, 2017 by Dan Williams Committed by Rafael J. Wysocki Apr 27, 2017

ACPI / sysfs: fix acpi_get_table() leak / acpi-sysfs denial of service



Reading an ACPI table through the /sys/firmware/acpi/tables interface
more than 65,536 times leads to the following log message:

 ACPI Error: Table ffff88033595eaa8, Validation count is zero after increment
  (20170119/tbutils-423)

...and the table being unavailable until the next reboot. Add the
missing acpi_put_table() so the table ->validation_count is decremented
after each read.

Reported-by: Anush Seetharaman <anush.seetharaman@intel.com>
Fixes: 174cc718 "ACPICA: Tables: Back port acpi_get_table_with_size() ..."
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Cc: 4.10+ <stable@vger.kernel.org> # 4.10+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

parent 5a7ad114

drivers/acpi/sysfs.c

+5 −2

Original line number	Diff line number	Diff line
		@@ -333,14 +333,17 @@ static ssize_t acpi_table_show(struct file filp, struct kobject kobj,
		container_of(bin_attr, struct acpi_table_attr, attr);
		struct acpi_table_header *table_header = NULL;
		acpi_status status;
		ssize_t rc;

		status = acpi_get_table(table_attr->name, table_attr->instance,
		&table_header);
		if (ACPI_FAILURE(status))
		return -ENODEV;

		return memory_read_from_buffer(buf, count, &offset,
		table_header, table_header->length);
		rc = memory_read_from_buffer(buf, count, &offset, table_header,
		table_header->length);
		acpi_put_table(table_header);
		return rc;
		}

		static int acpi_table_attr_init(struct kobject *tables_obj,

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