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memory: prevent dma-reentracy issues

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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>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20230427211013.2994127-2-alxndr@bu.edu>
[thuth: Replace warn_report() with warn_report_once()]
Signed-off-by: Thomas Huth <thuth@redhat.com>
This commit is contained in:
Alexander Bulekov 2023-04-27 17:10:06 -04:00 • committed by Thomas Huth
parent 3ee7f21ed2
commit a2e1753b80
3 changed files with 28 additions and 0 deletions
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7
include/hw/qdev-core.h
View file

@ -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 {