https://source.android.com/security/bulletin/2022-03-01
CVE-2020-29368
CVE-2021-39685
CVE-2021-39686
CVE-2021-39698
CVE-2021-3655
eventfd: track eventfd_signal() recursion depth
commit b5e683d5cab8cd433b06ae178621f083cabd4f63 upstream.
eventfd use cases from aio and io_uring can deadlock due to circular
or resursive calling, when eventfd_signal() tries to grab the waitqueue
lock. On top of that, it's also possible to construct notification
chains that are deep enough that we could blow the stack.
Add a percpu counter that tracks the percpu recursion depth, warn if we
exceed it. The counter is also exposed so that users of eventfd_signal()
can do the right thing if it's non-zero in the context where it is
called.
Cc: stable@vger.kernel.org # 4.19+
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2 files changed