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    Subject[PATCH 5.8 193/633] binder: Remove bogus warning on failed same-process transaction
    Date
    From: Jann Horn <jannh@google.com>

    [ Upstream commit e8b8ae7ce32e17a5c29f0289e9e2a39c7dcaa1b8 ]

    While binder transactions with the same binder_proc as sender and recipient
    are forbidden, transactions with the same task_struct as sender and
    recipient are possible (even though currently there is a weird check in
    binder_transaction() that rejects them in the target==0 case).
    Therefore, task_struct identities can't be used to distinguish whether
    the caller is running in the context of the sender or the recipient.

    Since I see no easy way to make this WARN_ON() useful and correct, let's
    just remove it.

    Fixes: 44d8047f1d87 ("binder: use standard functions to allocate fds")
    Reported-by: syzbot+e113a0b970b7b3f394ba@syzkaller.appspotmail.com
    Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
    Acked-by: Todd Kjos <tkjos@google.com>
    Signed-off-by: Jann Horn <jannh@google.com>
    Link: https://lore.kernel.org/r/20200806165359.2381483-1-jannh@google.com
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/android/binder.c | 2 --
    1 file changed, 2 deletions(-)

    diff --git a/drivers/android/binder.c b/drivers/android/binder.c
    index af85d37aef680..adab46ca5dff7 100644
    --- a/drivers/android/binder.c
    +++ b/drivers/android/binder.c
    @@ -2324,8 +2324,6 @@ static void binder_transaction_buffer_release(struct binder_proc *proc,
    * file is done when the transaction is torn
    * down.
    */
    - WARN_ON(failed_at &&
    - proc->tsk == current->group_leader);
    } break;
    case BINDER_TYPE_PTR:
    /*
    --
    2.25.1


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