On Fri, Sep 22, 2023 at 11:51 AM Alice Ryhl <aliceryhl@xxxxxxxxxx> wrote:
>
> On Fri, Sep 22, 2023 at 7:51 PM Carlos Llamas <cmllamas@xxxxxxxxxx> wrote:
> >
> > 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@xxxxxxxxxxxxxxx
> > Fixes: 0567461a7a6e ("binder: return pending info for frozen async txns")
> > Fixes: a7dc1e6f99df ("binder: tell userspace to dump current backtrace when detected oneway spamming")
> > Reported-by: syzbot+7f10c1653e35933c0f1e@xxxxxxxxxxxxxxxxxxxxxxxxx
> > Closes: https://syzkaller.appspot.com/bug?extid=7f10c1653e35933c0f1e
> > Suggested-by: Alice Ryhl <aliceryhl@xxxxxxxxxx>
> > Signed-off-by: Carlos Llamas <cmllamas@xxxxxxxxxx>
>
> Reviewed-by: Alice Ryhl <aliceryhl@xxxxxxxxxx>
Acked-by: Todd Kjos <tkjos@xxxxxxxxxx>
