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Subject[PATCH 4.11 056/115] ACPI / sysfs: fix acpi_get_table() leak / acpi-sysfs denial of service
4.11-stable review patch.  If anyone has any objections, please let me know.


From: Dan Williams <>

commit 0de0e198bc7191a0e46cf71f66fec4d07ca91396 upstream.

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

...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 <>
Fixes: 174cc7187e6f "ACPICA: Tables: Back port acpi_get_table_with_size() ..."
Signed-off-by: Dan Williams <>
Signed-off-by: Rafael J. Wysocki <>
Signed-off-by: Greg Kroah-Hartman <>

drivers/acpi/sysfs.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

--- a/drivers/acpi/sysfs.c
+++ b/drivers/acpi/sysfs.c
@@ -333,14 +333,17 @@ static ssize_t acpi_table_show(struct fi
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,
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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