ibmaem: prevent infinite probing loop on x3650 M2 systems

On older machines, probing for a nonexistent AEM interface returned an
IPMI error; when we saw this, we'd stop probing.  On the x3650 M2 and
(presumably) later, we are returned a value indicating success and a
buffer full of garbage or zeroes.  This causes the probe function to run
in an infinite loop.  To fix this, we add one last check--if the
interface number we're looking for is higher than the number of
interfaces that AEM claims to have, stop probing.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/hwmon/ibmaem.c b/drivers/hwmon/ibmaem.c
index 5e4775a62f6c..08c5179e6d84 100644
--- a/drivers/hwmon/ibmaem.c
+++ b/drivers/hwmon/ibmaem.c
@@ -676,7 +676,8 @@ static int aem_find_aem2(struct aem_ipmi_data *data,
                 return -ETIMEDOUT;
 
         if (data->rx_result || data->rx_msg_len != sizeof(*fi_resp) ||
-            memcmp(&fi_resp->id, &system_x_id, sizeof(system_x_id)))
+            memcmp(&fi_resp->id, &system_x_id, sizeof(system_x_id)) ||
+            fi_resp->num_instances <= instance_num)
                 return -ENOENT;
 
         return 0;