On Fri, Feb 23, 2018 at 07:24:20PM +0100, gregkh@xxxxxxxxxxxxxxxxxxx wrote:
> 4.4-stable review patch. If anyone has any objections, please let me know.
>
> ------------------
>
> From: Eric Biggers <ebiggers@xxxxxxxxxx>
>
> commit f88982679f54f75daa5b8eff3da72508f1e7422f upstream.
>
> If the kzalloc() in binder_get_thread() fails, binder_poll()
> dereferences the resulting NULL pointer.
>
> Fix it by returning POLLERR if the memory allocation failed.
>
> This bug was found by syzkaller using fault injection.
>
> Reported-by: syzbot <syzkaller@xxxxxxxxxxxxxxxx>
> Fixes: 457b9a6f09f0 ("Staging: android: add binder driver")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> ---
> drivers/android/binder.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> --- a/drivers/android/binder.c
> +++ b/drivers/android/binder.c
> @@ -2622,6 +2622,8 @@ static unsigned int binder_poll(struct f
> binder_lock(__func__);
>
> thread = binder_get_thread(proc);
> + if (!thread)
> + return POLLERR;
>
Noticed while merging into chromeos-4.4:
This will cause trouble in v4.4.y. Notice the call to "binder_lock(__func__)"
above. This call has been removed upstream, but not in v4.4.y. As a result,
the lock won't be released, which will result in subsequent hangups
if/when the function is called again.
v4.9.y has the same problem. v4.14.y+ are fine.
Greg - can you fix this up yourself or do you want me to send fixup
patches ? It might take a few days for me to get to it.
Guenter
> wait_for_proc_work = thread->transaction_stack == NULL &&
> list_empty(&thread->todo) && thread->return_error == BR_OK;