[LU-18995] Incorrect check for null from container_of()

• Type: Bug
• Resolution: Unresolved
• Priority: Minor
• Fix Version/s: Lustre 2.18.0
• Affects Version/s: Lustre 2.17.0
• Labels: smatch
• Severity: 3
• Assignee: WC Triage
• Reporter: Oleg Drokin

Description

Smatch highlight this incorrect pattern where we do an container_of from obd_device and then check it for null. Since the item we are looking for (kobj) is not the first item, the check is wrong.

 637 static ssize_t grant_shrink_store(struct kobject *kobj, struct attribute *attr,
 638                                   const char *buffer, size_t count)
 639 {
 640         struct obd_device *obd = container_of(kobj, struct obd_device,
 641                                               obd_kset.kobj);
 642         struct obd_import *imp;
 643         bool val;
 644         int rc;
 645 
 646         if (obd == NULL)
 647                 return 0;

We probably should drop all these checks as otherwise we'd long be crashing all around even before these accesses?

Functions affected:

stats_free, checksum_type_show, checksum_type_store, grant_shrink_store (twice, one in mdc and one in osc)