[LU-6520] Potential null pointer deref in mdt_stack_init and mdt_quota_init

• Type: Bug
• Resolution: Unresolved
• Priority: Minor
• Affects Version/s: Lustre 2.15.0
• Labels: smatch
• Severity: 3
• Assignee: WC Triage
• Reporter: Oleg Drokin

Description

smatch highlighted problematic code in mdt_stack_init and mdt_quota_init

        lcfg = lustre_cfg_new(LCFG_SETUP, bufs);
        if (lcfg == NULL)
                GOTO(class_detach, rc = -ENOMEM);
...
class_detach:
        if (rc)
                class_detach(obd, lcfg);
lcfg_cleanup:
        lustre_cfg_free(lcfg);

note that while lustre_cfs_Free is basically kfree, which is ok to work with NULL pointers, in reality it does

static inline void lustre_cfg_free(struct lustre_cfg *lcfg)
{
#ifdef __KERNEL__
        OBD_FREE(lcfg, lustre_cfg_len(lcfg->lcfg_bufcount, lcfg->lcfg_buflens));

which makes it not ok.