From: "zhangyi (F)" <yi.zhang@huawei.com>
To: <gregkh@linuxfoundation.org>
Cc: <linux-kernel@vger.kernel.org>, <linux-fsdevel@vger.kernel.org>,
<luto@kernel.org>, <adobriyan@gmail.com>,
<akpm@linux-foundation.org>, <vbabka@suse.cz>,
<peterz@infradead.org>, <bigeasy@linutronix.de>,
<mhocko@suse.com>, <john.ogness@linutronix.de>,
<yi.zhang@huawei.com>, <nixiaoming@huawei.com>
Subject: [PATCH 4.4 2/7] sched/core: Add try_get_task_stack() and put_task_stack()
Date: Mon, 2 Dec 2019 16:35:14 +0800 [thread overview]
Message-ID: <20191202083519.23138-3-yi.zhang@huawei.com> (raw)
In-Reply-To: <20191202083519.23138-1-yi.zhang@huawei.com>
From: Andy Lutomirski <luto@kernel.org>
commit c6c314a613cd7d03fb97713e0d642b493de42e69 upstream.
There are a few places in the kernel that access stack memory
belonging to a different task. Before we can start freeing task
stacks before the task_struct is freed, we need a way for those code
paths to pin the stack.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jann Horn <jann@thejh.net>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/17a434f50ad3d77000104f21666575e10a9c1fbd.1474003868.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: zhangyi (F) <yi.zhang@huawei.com>
---
include/linux/sched.h | 16 ++++++++++++++++
init/Kconfig | 3 +++
2 files changed, 19 insertions(+)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index d6b2e77aad3f..761247c966a5 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2858,11 +2858,19 @@ static inline struct thread_info *task_thread_info(struct task_struct *task)
{
return &task->thread_info;
}
+
+/*
+ * When accessing the stack of a non-current task that might exit, use
+ * try_get_task_stack() instead. task_stack_page will return a pointer
+ * that could get freed out from under you.
+ */
static inline void *task_stack_page(const struct task_struct *task)
{
return task->stack;
}
+
#define setup_thread_stack(new,old) do { } while(0)
+
static inline unsigned long *end_of_stack(const struct task_struct *task)
{
return task->stack;
@@ -2898,6 +2906,14 @@ static inline unsigned long *end_of_stack(struct task_struct *p)
}
#endif
+
+static inline void *try_get_task_stack(struct task_struct *tsk)
+{
+ return task_stack_page(tsk);
+}
+
+static inline void put_task_stack(struct task_struct *tsk) {}
+
#define task_stack_end_corrupted(task) \
(*(end_of_stack(task)) != STACK_END_MAGIC)
diff --git a/init/Kconfig b/init/Kconfig
index 5dec7d424980..f9fb621c9562 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -33,6 +33,9 @@ config THREAD_INFO_IN_TASK
make this work, an arch will need to remove all thread_info fields
except flags and fix any runtime bugs.
+ One subtle change that will be needed is to use try_get_task_stack()
+ and put_task_stack() in save_thread_stack_tsk() and get_wchan().
+
menu "General setup"
config BROKEN
--
2.17.2
next prev parent reply other threads:[~2019-12-02 8:14 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-02 8:35 [PATCH 4.4 0/7] fs/proc: Stop reporting eip and esp in zhangyi (F)
2019-12-02 8:35 ` [PATCH 4.4 1/7] sched/core: Allow putting thread_info into task_struct zhangyi (F)
2019-12-02 8:35 ` zhangyi (F) [this message]
2019-12-02 8:35 ` [PATCH 4.4 3/7] sched/core, x86: Make struct thread_info arch specific again zhangyi (F)
2019-12-02 8:35 ` [PATCH 4.4 4/7] fs/proc: Stop reporting eip and esp in /proc/PID/stat zhangyi (F)
2019-12-02 8:35 ` [PATCH 4.4 5/7] fs/proc: Report eip/esp in /prod/PID/stat for coredumping zhangyi (F)
2019-12-02 8:35 ` [PATCH 4.4 6/7] proc: fix coredump vs read /proc/*/stat race zhangyi (F)
2019-12-02 8:35 ` [PATCH 4.4 7/7] fs/proc/array.c: allow reporting eip/esp for all coredumping threads zhangyi (F)
2019-12-12 17:15 ` [PATCH 4.4 0/7] fs/proc: Stop reporting eip and esp in Greg KH
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