linux-kernel - [PATCH] android: binder: Sanity check at binder ioctl

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Message-ID: <1453173762-130234-1-git-send-email-puck.chen@hisilicon.com>
Date:	Tue, 19 Jan 2016 11:22:42 +0800
From:	Chen Feng <puck.chen@...ilicon.com>
To:	<puck.chen@...ilicon.com>, <gregkh@...uxfoundation.org>,
	<arve@...roid.com>, <riandrews@...roid.com>,
	<devel@...verdev.osuosl.org>, <linux-kernel@...r.kernel.org>,
	<yudongbin@...ilicon.com>, <saberlily.xia@...ilicon.com>,
	<suzhuangluan@...ilicon.com>, <kong.kongxinwei@...ilicon.com>,
	<xuyiping@...ilicon.com>, <z.liuxinliang@...ilicon.com>,
	<weidong2@...ilicon.com>, <w.f@...wei.com>,
	<puck.chen@...mail.com>, <shimingxing@...ilicon.com>,
	<oliver.fu@...ilicon.com>, <albert.lubing@...ilicon.com>,
	<chenxiang9@...wei.com>, <liuzixing@...wei.com>,
	<haojian.zhuang@...aro.org>, <zhaojunmin@...wei.com>,
	<wangjing6@...wei.com>, <rientjes@...gle.com>,
	<john.stultz@...aro.org>
CC:	<qijiwen@...ilicon.com>, <peter.panshilin@...ilicon.com>,
	<dan.zhao@...ilicon.com>, <linuxarm@...wei.com>,
	<dev@...ts.96boards.org>
Subject: [PATCH] android: binder: Sanity check at binder ioctl

When a process fork a child process, we should not allow the
child process use the binder which opened by parent process.

But if the binder-object creater is a thread of one process who exit,
the other thread can also use this binder-object normally.
We can distinguish this by the member proc->tsk->mm.
If the thread exit the tsk->mm will be NULL.

proc->tsk->mm != current->tsk->mm && proc->tsk->mm

So only allow the shared mm_struct to use the same binder-object and
check the existence of mm_struct.

Signed-off-by: Chen Feng <puck.chen@...ilicon.com>
Signed-off-by: Wei  Dong <weidong2@...ilicon.com>
Signed-off-by: Junmin Zhao <zhaojunmin@...wei.com>
Reviewed-by: Zhuangluan Su <suzhuangluan@...ilicon.com>
---
 drivers/android/binder.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index a39e85f..3a74c5d 100644
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -2736,6 +2736,8 @@ static long binder_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 
 	/*pr_info("binder_ioctl: %d:%d %x %lx\n",
 			proc->pid, current->pid, cmd, arg);*/
+	if (unlikely(proc->tsk->mm != current->tsk->mm && proc->tsk->mm))
+		return -EINVAL;
 
 	trace_binder_ioctl(cmd, arg);
 
-- 
1.9.1