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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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5
include/exec/memory.h
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@ -767,6 +767,8 @@ struct MemoryRegion {
bool is_iommu;
RAMBlock *ram_block;
Object *owner;
/* owner as TYPE_DEVICE. Used for re-entrancy checks in MR access hotpath */
DeviceState *dev;
const MemoryRegionOps *ops;
void *opaque;
@ -791,6 +793,9 @@ struct MemoryRegion {
unsigned ioeventfd_nb;
MemoryRegionIoeventfd *ioeventfds;
RamDiscardManager *rdm; /* Only for RAM */
/* For devices designed to perform re-entrant IO into their own IO MRs */
bool disable_reentrancy_guard;
};
struct IOMMUMemoryRegion {