[LU-11612] Potential null pointer dereference in new_init_ucred

• Type: Bug
• Resolution: Unresolved
• Priority: Minor
• Affects Version/s: Lustre 2.12.0, Lustre 2.10.5
• Labels: easy
• Severity: 3
• Assignee: WC Triage
• Reporter: Oleg Drokin

Description

The code looks like this:

        setgid = ((pud->pud_gid != pud->pud_fsgid) ||
                  (ucred->uc_identity &&
                   (pud->pud_gid != ucred->uc_identity->mi_gid)));
...
        if (setgid && !(perm & CFS_SETGID_PERM)) {
                CDEBUG(D_SEC, "mdt blocked setgid attempt (%u:%u/%u:%u -> %u) "
                       "from %s\n", pud->pud_uid, pud->pud_gid,
                       pud->pud_fsuid, pud->pud_fsgid,
                       ucred->uc_identity->mi_gid, libcfs_nid2str(peernid));
                GOTO(out, rc = -EACCES);
        }

So the posssibility seems to be pretty real though typically D_SEC is not defined so no crash like that by default.