Re: [PATCH v8 1/8] memory: prevent dma-reentracy issues

[Thomas Huth]

On 21/04/2023 16.27, Alexander Bulekov wrote:
> Add a flag to the DeviceState, when a device is engaged in PIO/MMIO/DMA.
> This flag is set/checked prior to calling a device's MemoryRegion
> handlers, and set when device code initiates DMA.  The purpose of this
> flag is to prevent two types of DMA-based reentrancy issues:
>
> 1.) mmio -> dma -> mmio case
> 2.) bh -> dma write -> mmio case
>
> These issues have led to problems such as stack-exhaustion and
> use-after-frees.
>
> Summary of the problem from Peter Maydell:
> https://lore.kernel.org/qemu-devel/CAFEAcA_23vc7hE3iaM-JVA6W38LK4hJoWae5KcknhPRD5fPBZA@mail.gmail.com
>
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/62
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/540
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/541
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/556
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/557
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/827
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1282
> Resolves: CVE-2023-0330
>
> Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
> ---
>   include/exec/memory.h  |  2 ++
>   include/hw/qdev-core.h |  7 +++++++
>   softmmu/memory.c       | 14 ++++++++++++++
>   softmmu/trace-events   |  1 +
>   4 files changed, 24 insertions(+)

Reviewed-by: Thomas Huth <thuth@redhat.com>