[LU-11911] lov_iocontrol: BUG: unable to handle kernel NULL pointer dereference at 0000000000000100

• Type: Bug
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.13.0, Lustre 2.12.4
• Severity: 3
• Assignee: Vladimir Saveliev
• Reporter: Vladimir Saveliev

Description

For inactive OST lov->lov_tgts[index]->ltd_exp is NULL, it should be checked before accessing lov->lov_tgts[index]->ltd_exp->exp_obd.

static int lov_iocontrol(unsigned int cmd, struct obd_export *exp, int len,
                         void *karg, void __user *uarg)
...
                imp = lov->lov_tgts[index]->ltd_exp->exp_obd->u.cli.cl_import;
                if (!lov->lov_tgts[index]->ltd_active &&
                    imp->imp_state != LUSTRE_IMP_IDLE)
                        RETURN(-ENODATA);
...

The problem can be seen with:

# REFORMAT=yes sh llmount.sh
# lctl conf_param lustre-OST0001.osc.active=0
# sh llmountcleanup.sh
# NOFORMAT=yes sh llmount.sh
# lfs df

It causes:

[ 2659.212961] BUG: unable to handle kernel NULL pointer dereference at 0000000000000100
[ 2659.216168] IP: [<ffffffffc0cbd3b8>] lov_iocontrol+0x308/0x21f0 [lov]