Commit-ID: 382005027fedc50b28d40ae64ef1461cca38953e Gitweb: http://git.kernel.org/tip/382005027fedc50b28d40ae64ef1461cca38953e Author: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> AuthorDate: Wed, 2 Nov 2016 19:50:29 +0900 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitDate: Thu, 3 Nov 2016 07:27:34 +0100 sched/core: Fix oops in sched_show_task() When CONFIG_THREAD_INFO_IN_TASK=y, it is possible that an exited thread remains in the task list after its stack pointer was already set to NULL. Therefore, thread_saved_pc() and stack_not_used() in sched_show_task() will trigger NULL pointer dereference if an attempt to dump such thread's traces (e.g. SysRq-t, khungtaskd) is made. Since show_stack() in sched_show_task() calls try_get_task_stack() and sched_show_task() is called from interrupt context, calling try_get_task_stack() from sched_show_task() will be safe as well. Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> Acked-by: Andy Lutomirski <luto@xxxxxxxxxx> Acked-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: bp@xxxxxxxxx Cc: brgerst@xxxxxxxxx Cc: jann@xxxxxxxxx Cc: keescook@xxxxxxxxxxxx Cc: linux-api@xxxxxxxxxxxxxxx Cc: tycho.andersen@xxxxxxxxxxxxx Link: http://lkml.kernel.org/r/201611021950.FEJ34368.HFFJOOMLtQOVSF@xxxxxxxxxxxxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> --- kernel/sched/core.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 42d4027..9abf66b 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -5192,6 +5192,8 @@ void sched_show_task(struct task_struct *p) int ppid; unsigned long state = p->state; + if (!try_get_task_stack(p)) + return; if (state) state = __ffs(state) + 1; printk(KERN_INFO "%-15.15s %c", p->comm, @@ -5221,6 +5223,7 @@ void sched_show_task(struct task_struct *p) print_worker_info(KERN_INFO, p); show_stack(p, NULL); + put_task_stack(p); } void show_state_filter(unsigned long state_filter) -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
|