linux-kernel - [PATCH] binder: fix handling of misaligned binder object

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Message-Id: <20190214232257.76856-1-tkjos@google.com>
Date:   Thu, 14 Feb 2019 15:22:57 -0800
From:   Todd Kjos <tkjos@...roid.com>
To:     tkjos@...gle.com, gregkh@...uxfoundation.org, arve@...roid.com,
        devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org,
        maco@...gle.com
Cc:     joel@...lfernandes.org, kernel-team@...roid.com,
        syzbot+55de1eb4975dec156d8f@...kaller.appspotmail.com
Subject: [PATCH] binder: fix handling of misaligned binder object

Fixes crash found by syzbot:
kernel BUG at drivers/android/binder_alloc.c:LINE! (2)

Reported-by: syzbot+55de1eb4975dec156d8f@...kaller.appspotmail.com
Signed-off-by: Todd Kjos <tkjos@...gle.com>
---
Applies to linux-next

 drivers/android/binder.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index 2dba539eb792c..8685882da64cd 100644
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -2057,7 +2057,7 @@ static size_t binder_get_object(struct binder_proc *proc,
 	size_t object_size = 0;
 
 	read_size = min_t(size_t, sizeof(*object), buffer->data_size - offset);
-	if (read_size < sizeof(*hdr))
+	if (read_size < sizeof(*hdr) || !IS_ALIGNED(offset, sizeof(u32)))
 		return 0;
 	binder_alloc_copy_from_buffer(&proc->alloc, object, buffer,
 				      offset, read_size);
-- 
2.21.0.rc0.258.g878e2cd30e-goog