Alakesh Haloi <[email protected]> writes: > There has been at least one occurrence where a null pointer derefernce > panic was seen with following stack trace. > > #0 [ffffff800bcd3800] machine_kexec at ffffff8008095fb4 > #1 [ffffff800bcd3860] __crash_kexec at ffffff8008122a30 > #2 [ffffff800bcd39f0] panic at ffffff80080aa054 > #3 [ffffff800bcd3ae0] die at ffffff800808aee8 > #4 [ffffff800bcd3b20] die_kernel_fault at ffffff8008099520 > #5 [ffffff800bcd3b50] __do_kernel_fault at ffffff8008098e50 > #6 [ffffff800bcd3b80] do_translation_fault at ffffff800809929c > #7 [ffffff800bcd3b90] do_mem_abort at ffffff8008081204 > #8 [ffffff800bcd3d90] el1_ia at ffffff800808304c > PC: ffffff80080c20ec [pid_nr_ns+4] > LR: ffffff80080c231c [__task_pid_nr_ns+72] > SP: ffffff800bcd3da0 PSTATE: 60000005 > X29: ffffff800bcd3da0 X28: ffffffc00691c380 X27: 0000000000000001 > X26: 00000000004ce8e8 X25: 00000000004ce8d0 X24: ffffffc00691c3e0 > X23: ffffffc004e8c000 X22: 0000000000000000 X21: ffffffc00b042ed2 > X20: ffffff800876a4f0 X19: 0000000000000000 X18: 0000000000000000 > X17: 0000000000000001 X16: 0000000000000000 X15: 0000000000000000 > X14: 0000000400000003 X13: 0000000000000008 X12: fefefefefefefeff > X11: 0000000000000000 X10: 0000007fffffffff X9: 00000000004ce8b0 > X8: 00000000004ce8b0 X7: 0000000000000000 X6: ffffffc00b042ed2 > X5: ffffffc00b042ed2 X4: 0000000000020008 X3: 53206e69616c702f > X2: ffffff800876a4f0 X1: ffffff800876a4f0 X0: 53206e69616c702f > #9 [ffffff800bcd3da0] pid_nr_ns at ffffff80080c20e8
I am still thinking this through. What called pid_nr_ns with a NULL pid namespace? That was not apparent from the backtrace you provided. Maybe it is sane to check for NULL but it may be preferable to fix the caller. Eric > Signed-off-by: Alakesh Haloi <[email protected]> > Cc: [email protected] > --- > kernel/pid.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/pid.c b/kernel/pid.c > index a96bc4bf4f86..3767b9e1431d 100644 > --- a/kernel/pid.c > +++ b/kernel/pid.c > @@ -474,7 +474,7 @@ pid_t pid_nr_ns(struct pid *pid, struct pid_namespace *ns) > struct upid *upid; > pid_t nr = 0; > > - if (pid && ns->level <= pid->level) { > + if (pid && ns && ns->level <= pid->level) { > upid = &pid->numbers[ns->level]; > if (upid->ns == ns) > nr = upid->nr;
