From: Carlos Llamas cmllamas@google.com

stable inclusion from stable-v4.19.307 commit dd64bb8329ce0ea27bc557e4160c2688835402ac category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I93X0G CVE: CVE-2024-26606

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...

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commit 97830f3c3088638ff90b20dfba2eb4d487bf14d7 upstream.

In (e)poll mode, threads often depend on I/O events to determine when data is ready for consumption. Within binder, a thread may initiate a command via BINDER_WRITE_READ without a read buffer and then make use of epoll_wait() or similar to consume any responses afterwards.

It is then crucial that epoll threads are signaled via wakeup when they queue their own work. Otherwise, they risk waiting indefinitely for an event leaving their work unhandled. What is worse, subsequent commands won't trigger a wakeup either as the thread has pending work.

Fixes: 457b9a6f09f0 ("Staging: android: add binder driver") Cc: Arve Hjønnevåg arve@android.com Cc: Martijn Coenen maco@android.com Cc: Alice Ryhl aliceryhl@google.com Cc: Steven Moreland smoreland@google.com Cc: stable@vger.kernel.org # v4.19+ Signed-off-by: Carlos Llamas cmllamas@google.com Link: https://lore.kernel.org/r/20240131215347.1808751-1-cmllamas@google.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Zhang Xiaoxu zhangxiaoxu5@huawei.com --- drivers/android/binder.c | 10 ++++++++++ 1 file changed, 10 insertions(+)

diff --git a/drivers/android/binder.c b/drivers/android/binder.c index 98c785ebfa5d..f98d84c5c695 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -880,6 +880,16 @@ binder_enqueue_thread_work_ilocked(struct binder_thread *thread, { WARN_ON(!list_empty(&thread->waiting_thread_node)); binder_enqueue_work_ilocked(work, &thread->todo); + + /* (e)poll-based threads require an explicit wakeup signal when + * queuing their own work; they rely on these events to consume + * messages without I/O block. Without it, threads risk waiting + * indefinitely without handling the work. + */ + if (thread->looper & BINDER_LOOPER_STATE_POLL && + thread->pid == current->pid && !thread->process_todo) + wake_up_interruptible_sync(&thread->wait); + thread->process_todo = true; }