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authorTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>2016-11-02 19:50:29 +0900
committerIngo Molnar <mingo@kernel.org>2016-11-03 07:27:34 +0100
commit382005027fedc50b28d40ae64ef1461cca38953e (patch)
tree61e49510637dc732803389e7920f206946dc0afd /kernel
parent0c183d92b20b5c84ca655b45ef57b3318b83eb9e (diff)
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@I-love.SAKURA.ne.jp> Acked-by: Andy Lutomirski <luto@kernel.org> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: bp@alien8.de Cc: brgerst@gmail.com Cc: jann@thejh.net Cc: keescook@chromium.org Cc: linux-api@vger.kernel.org Cc: tycho.andersen@canonical.com Link: http://lkml.kernel.org/r/201611021950.FEJ34368.HFFJOOMLtQOVSF@I-love.SAKURA.ne.jp Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched/core.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 42d4027f9e26..9abf66b6c271 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)