From a2e1753b8054344f32cf94f31c6399a58794a380 Mon Sep 17 00:00:00 2001 From: Alexander Bulekov Date: Thu, 27 Apr 2023 17:10:06 -0400 Subject: memory: prevent dma-reentracy issues 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 Reviewed-by: Thomas Huth Message-Id: <20230427211013.2994127-2-alxndr@bu.edu> [thuth: Replace warn_report() with warn_report_once()] Signed-off-by: Thomas Huth --- include/hw/qdev-core.h | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'include/hw/qdev-core.h') diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h index bd50ad5ee1..7623703943 100644 --- a/include/hw/qdev-core.h +++ b/include/hw/qdev-core.h @@ -162,6 +162,10 @@ struct NamedClockList { QLIST_ENTRY(NamedClockList) node; }; +typedef struct { + bool engaged_in_io; +} MemReentrancyGuard; + /** * DeviceState: * @realized: Indicates whether the device has been fully constructed. @@ -194,6 +198,9 @@ struct DeviceState { int alias_required_for_version; ResettableState reset; GSList *unplug_blockers; + + /* Is the device currently in mmio/pio/dma? Used to prevent re-entrancy */ + MemReentrancyGuard mem_reentrancy_guard; }; struct DeviceListener { -- cgit 1.4.1