• Carlos Llamas's avatar
    binder: fix memory leaks of spam and pending work · 1aa3aaf8
    Carlos Llamas authored
    A transaction complete work is allocated and queued for each
    transaction. Under certain conditions the work->type might be marked as
    BINDER_WORK_TRANSACTION_ONEWAY_SPAM_SUSPECT to notify userspace about
    potential spamming threads or as BINDER_WORK_TRANSACTION_PENDING when
    the target is currently frozen.
    
    However, these work types are not being handled in binder_release_work()
    so they will leak during a cleanup. This was reported by syzkaller with
    the following kmemleak dump:
    
    BUG: memory leak
    unreferenced object 0xffff88810e2d6de0 (size 32):
      comm "syz-executor338", pid 5046, jiffies 4294968230 (age 13.590s)
      hex dump (first 32 bytes):
        e0 6d 2d 0e 81 88 ff ff e0 6d 2d 0e 81 88 ff ff  .m-......m-.....
        04 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
      backtrace:
        [<ffffffff81573b75>] kmalloc_trace+0x25/0x90 mm/slab_common.c:1114
        [<ffffffff83d41873>] kmalloc include/linux/slab.h:599 [inline]
        [<ffffffff83d41873>] kzalloc include/linux/slab.h:720 [inline]
        [<ffffffff83d41873>] binder_transaction+0x573/0x4050 drivers/android/binder.c:3152
        [<ffffffff83d45a05>] binder_thread_write+0x6b5/0x1860 drivers/android/binder.c:4010
        [<ffffffff83d486dc>] binder_ioctl_write_read drivers/android/binder.c:5066 [inline]
        [<ffffffff83d486dc>] binder_ioctl+0x1b2c/0x3cf0 drivers/android/binder.c:5352
        [<ffffffff816b25f2>] vfs_ioctl fs/ioctl.c:51 [inline]
        [<ffffffff816b25f2>] __do_sys_ioctl fs/ioctl.c:871 [inline]
        [<ffffffff816b25f2>] __se_sys_ioctl fs/ioctl.c:857 [inline]
        [<ffffffff816b25f2>] __x64_sys_ioctl+0xf2/0x140 fs/ioctl.c:857
        [<ffffffff84b30008>] do_syscall_x64 arch/x86/entry/common.c:50 [inline]
        [<ffffffff84b30008>] do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
        [<ffffffff84c0008b>] entry_SYSCALL_64_after_hwframe+0x63/0xcd
    
    Fix the leaks by kfreeing these work types in binder_release_work() and
    handle them as a BINDER_WORK_TRANSACTION_COMPLETE cleanup.
    
    Cc: stable@vger.kernel.org
    Fixes: 0567461a ("binder: return pending info for frozen async txns")
    Fixes: a7dc1e6f ("binder: tell userspace to dump current backtrace when detected oneway spamming")
    Reported-by: syzbot+7f10c1653e35933c0f1e@syzkaller.appspotmail.com
    Closes: https://syzkaller.appspot.com/bug?extid=7f10c1653e35933c0f1eSuggested-by: default avatarAlice Ryhl <aliceryhl@google.com>
    Signed-off-by: default avatarCarlos Llamas <cmllamas@google.com>
    Reviewed-by: default avatarAlice Ryhl <aliceryhl@google.com>
    Acked-by: default avatarTodd Kjos <tkjos@google.com>
    Link: https://lore.kernel.org/r/20230922175138.230331-1-cmllamas@google.comSigned-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    1aa3aaf8
binder.c 186 KB