Messages in this thread Patch in this message | | | From | Schspa Shi <> | Subject | [PATCH] binder: fix atomic sleep when get extended error | Date | Wed, 18 May 2022 01:52:25 +0800 |
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binder_inner_proc_lock(thread->proc) is a spin lock, copy_to_user can't be called with in this lock.
Copy it as a local variable, and check the id to make sure the user space gets the latest error message
Reported-by: syzbot+46fff6434a7f968ecb39@syzkaller.appspotmail.com Fixes: bd32889e841c ("binder: add BINDER_GET_EXTENDED_ERROR ioctl") Signed-off-by: Schspa Shi <schspa@gmail.com> --- drivers/android/binder.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-)
diff --git a/drivers/android/binder.c b/drivers/android/binder.c index d9253b2a7bd9..5f2e1fa3da74 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -5163,13 +5163,20 @@ static int binder_ioctl_get_extended_error(struct binder_thread *thread, void __user *ubuf) { struct binder_extended_error *ee = &thread->ee; + struct binder_extended_error eeb; binder_inner_proc_lock(thread->proc); - if (copy_to_user(ubuf, ee, sizeof(*ee))) { - binder_inner_proc_unlock(thread->proc); +retry: + eeb = *ee; + binder_inner_proc_unlock(thread->proc); + if (copy_to_user(ubuf, &eeb, sizeof(eeb))) return -EFAULT; - } + binder_inner_proc_lock(thread->proc); + if (eeb.id != ee->id) { + /* retry to get newest error info */ + goto retry; + } ee->id = 0; ee->command = BR_OK; ee->param = 0; -- 2.24.3 (Apple Git-128)
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