From 24e54ffd435c59aa91f932bbfcf19494c3f50f4c Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Tue, 30 Jan 2018 23:11:24 -0800 Subject: [PATCH] binder: check for binder_thread allocation failure in binder_poll() 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 Fixes: 457b9a6f09f0 ("Staging: android: add binder driver") Signed-off-by: Eric Biggers Signed-off-by: Greg Kroah-Hartman [bwh: Backported to 3.16: - Drop the binder global lock before returning - Adjust filename] Signed-off-by: Ben Hutchings --- drivers/staging/android/binder.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/staging/android/binder.c b/drivers/staging/android/binder.c index f83680cc115d..f2d448ab17e2 100644 --- a/drivers/staging/android/binder.c +++ b/drivers/staging/android/binder.c @@ -2572,6 +2572,10 @@ static unsigned int binder_poll(struct file *filp, binder_lock(__func__); thread = binder_get_thread(proc); + if (!thread) { + binder_unlock(__func__); + return POLLERR; + } wait_for_proc_work = thread->transaction_stack == NULL && list_empty(&thread->todo) && thread->return_error == BR_OK;