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android: binder: Sanity check at binder ioctl

Message ID 1453173762-130234-1-git-send-email-puck.chen@hisilicon.com
State Superseded
Headers show

Commit Message

Chen Feng Jan. 19, 2016, 3:22 a.m. UTC 
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@hisilicon.com>

Signed-off-by: Wei  Dong <weidong2@hisilicon.com>

Signed-off-by: Junmin Zhao <zhaojunmin@huawei.com>

Reviewed-by: Zhuangluan Su <suzhuangluan@hisilicon.com>

---
 drivers/android/binder.c | 2 ++
 1 file changed, 2 insertions(+)

-- 
1.9.1
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Patch

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);