[LU-15634] Use after free in ptlrpc

• Type: Bug
• Resolution: Fixed
• Priority: Critical
• Fix Version/s: Lustre 2.15.0
• Affects Version/s: Lustre 2.14.0, Lustre 2.15.0
• Severity: 3
• Assignee: Shaun Tancheff
• Reporter: Shaun Tancheff

Description

ptlrpc: Use after free of 'conn' in rhashtable retry

Use after free of 'conn' in the uncommon case of
rhashtable_lookup_get_insert_fast failing with -EBUSY or -ENOMEM

Move OBD_FREE_PTR(conn) below the retry and set conn2 to NULL
on error, propagating to conn and returning to the caller.

Fixes: 37b29a8f70 ("LU-8130 ptlrpc: convert conn_hash to rhashtable");