[PATCH AUTOSEL 6.1 05/21] exit: Detect and fix irq disabled state in oops

Sasha Levin
2023-02-26T03:44:32Z

From: Nicholas Piggin <npiggin@gmail.com>

[ Upstream commit 001c28e57187570e4b5aa4492c7a957fb6d65d7b ]

If a task oopses with irqs disabled, this can cause various cascading
problems in the oops path such as sleep-from-invalid warnings, and
potentially worse.

Since commit 0258b5fd7c712 ("coredump: Limit coredumps to a single
thread group"), the unconditional irq enable in coredump_task_exit()
will "fix" the irq state to be enabled early in do_exit(), so currently
this may not be triggerable, but that is coincidental and fragile.

Detect and fix the irqs_disabled() condition in the oops path before
calling do_exit(), similarly to the way in_atomic() is handled.

Reported-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Link: https://lore.kernel.org/lkml/20221004094401.708299-1-npiggin@gmail.com/
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
kernel/exit.c | 7 +++++++
1 file changed, 7 insertions(+)

diff --git a/kernel/exit.c b/kernel/exit.c
index 15dc2ec80c467..bccfa4218356e 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -807,6 +807,8 @@ void __noreturn do_exit(long code)
struct task_struct *tsk = current;
int group_dead;

+ WARN_ON(irqs_disabled());
+
synchronize_group_exit(tsk, code);

WARN_ON(tsk->plug);
@@ -938,6 +940,11 @@ void __noreturn make_task_dead(int signr)
if (unlikely(!tsk->pid))
panic("Attempted to kill the idle task!");

+ if (unlikely(irqs_disabled())) {
+ pr_info("note: %s[%d] exited with irqs disabled\n",
+ current->comm, task_pid_nr(current));
+ local_irq_enable();
+ }
if (unlikely(in_atomic())) {
pr_info("note: %s[%d] exited with preempt_count %d\n",
current->comm, task_pid_nr(current),
--
2.39.0