[LU-14959] Users of ldlm_resource_get much check return value

• Type: Bug
• Resolution: Fixed
• Priority: Major
• Fix Version/s: Lustre 2.15.0
• Severity: 3
• Assignee: Oleg Drokin
• Reporter: Oleg Drokin

Description

osc_req_attr_set() and mdc_get_lock_handle() use result from ldlm_resource_get() without checking it's not IS_ERR() resulting in a NULL pointer dereference crash in ldlm_resource_dump()

It's less critical in osc_req_attr_set where the branch culminates in LBUG anyway, but mdc_get_lock_handle seems to be a real unintended crash.

Both cases seem to be worth fixing and also comment for ldlm_resource_get is incorrect since it no longer returns NULL for the error