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    Subject[PATCH 4.4 49/75] sched: panic on corrupted stack end
    Date
    4.4-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Jann Horn <jannh@google.com>

    commit 29d6455178a09e1dc340380c582b13356227e8df upstream.

    Until now, hitting this BUG_ON caused a recursive oops (because oops
    handling involves do_exit(), which calls into the scheduler, which in
    turn raises an oops), which caused stuff below the stack to be
    overwritten until a panic happened (e.g. via an oops in interrupt
    context, caused by the overwritten CPU index in the thread_info).

    Just panic directly.

    Signed-off-by: Jann Horn <jannh@google.com>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    kernel/sched/core.c | 3 ++-
    1 file changed, 2 insertions(+), 1 deletion(-)

    --- a/kernel/sched/core.c
    +++ b/kernel/sched/core.c
    @@ -3008,7 +3008,8 @@ static noinline void __schedule_bug(stru
    static inline void schedule_debug(struct task_struct *prev)
    {
    #ifdef CONFIG_SCHED_STACK_END_CHECK
    - BUG_ON(task_stack_end_corrupted(prev));
    + if (task_stack_end_corrupted(prev))
    + panic("corrupted stack end detected inside scheduler\n");
    #endif

    if (unlikely(in_atomic_preempt_off())) {

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