From: Eric Biggers <ebiggers@google.com>
Date: Wed, 31 Jan 2018 07:11:24 +0000 (-0800)
Subject: binder: check for binder_thread allocation failure in binder_poll()
X-Git-Tag: v4.9.84~108
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4be5a281048964854c0b1c145e57597e7116ea9f;p=thirdparty%2Fkernel%2Fstable.git

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

diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index 15009b2b33c7b..3b6ac80b21272 100644
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -2628,6 +2628,8 @@ static unsigned int binder_poll(struct file *filp,
 	binder_lock(__func__);
 
 	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;