4.4-stable review patch.  If anyone has any objections, please let me know.


From: Eric Biggers <ebigg...@google.com>

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 <syzkal...@googlegroups.com>
Fixes: 457b9a6f09f0 ("Staging: android: add binder driver")
Cc: sta...@vger.kernel.org
Signed-off-by: Eric Biggers <ebigg...@google.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

 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
        thread = binder_get_thread(proc);
+       if (!thread)
+               return POLLERR;
        wait_for_proc_work = thread->transaction_stack == NULL &&
                list_empty(&thread->todo) && thread->return_error == BR_OK;

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