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From:   Ondrej Mosnacek <omosnace@redhat.com>
Date:   Mon, 8 Aug 2022 12:13:17 +0200
Message-ID: <CAFqZXNtNjQLpzu4CFiMawfkKeVFULw4ti3MdZL1QejPrzeJv8Q@mail.gmail.com>
Subject: Binder regression caused by commit a43cfc87caaf
To:     "Liam R. Howlett" <Liam.Howlett@oracle.com>,
        Andrew Morton <akpm@linux-foundation.org>
Cc:     Minchan Kim <minchan@kernel.org>,
        "Christian Brauner (Microsoft)" <brauner@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Hridya Valsaraju <hridya@google.com>,
        Joel Fernandes <joel@joelfernandes.org>,
        Martijn Coenen <maco@android.com>,
        Suren Baghdasaryan <surenb@google.com>,
        Todd Kjos <tkjos@android.com>,
        "Matthew Wilcox (Oracle)" <willy@infradead.org>,
        Linux kernel mailing list <linux-kernel@vger.kernel.org>,
        =?UTF-8?B?QXJ2ZSBIasO4bm5ldsOlZw==?= <arve@android.com>,
        Carlos Llamas <cmllamas@google.com>
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Hello,

FYI, since commit a43cfc87caaf ("android: binder: stop saving a
pointer to the VMA") (found by git bisect) the binder test in
selinux-testsuite [1] started to trigger a lockdep assert BUG() in
find_vma() - see the end of [2] for an example.

A minimal reproducer is:
```
git clone https://github.com/SELinuxProject/selinux-testsuite.git
cd selinux-testsuite/tests/binder
make
setenforce 0  # if SELinux is enabled
./init_binder.sh || true
./manager -n -v & sleep 2
./service_provider -n -v
```
Requires the equivalent of libselinux-devel, make, gcc, and git-core
Fedora packages.
The last command will trigger the BUG; on good kernels it will
successfully enter the ioctl loop.

[1] https://github.com/SELinuxProject/selinux-testsuite/
[2] https://s3.us-east-1.amazonaws.com/arr-cki-prod-datawarehouse-public/datawarehouse-public/2022/08/07/redhat:606549366/build_x86_64_redhat:606549366_x86_64/tests/5/results_0001/console.log/console.log

-- 
Ondrej Mosnacek
Senior Software Engineer, Linux Security - SELinux kernel
Red Hat, Inc.