mirror of https://github.com/proxmox/mirror_qemu
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 <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>
(cherry picked from commit a2e1753b80
)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
parent
590e71e536
commit
c40ca2301c
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@ -741,6 +741,8 @@ struct MemoryRegion {
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bool is_iommu;
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RAMBlock *ram_block;
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Object *owner;
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/* owner as TYPE_DEVICE. Used for re-entrancy checks in MR access hotpath */
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DeviceState *dev;
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const MemoryRegionOps *ops;
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void *opaque;
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@ -765,6 +767,9 @@ struct MemoryRegion {
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unsigned ioeventfd_nb;
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MemoryRegionIoeventfd *ioeventfds;
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RamDiscardManager *rdm; /* Only for RAM */
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/* For devices designed to perform re-entrant IO into their own IO MRs */
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bool disable_reentrancy_guard;
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};
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struct IOMMUMemoryRegion {
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@ -162,6 +162,10 @@ struct NamedClockList {
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QLIST_ENTRY(NamedClockList) node;
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};
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typedef struct {
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bool engaged_in_io;
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} MemReentrancyGuard;
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/**
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* DeviceState:
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* @realized: Indicates whether the device has been fully constructed.
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@ -194,6 +198,9 @@ struct DeviceState {
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int alias_required_for_version;
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ResettableState reset;
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GSList *unplug_blockers;
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/* Is the device currently in mmio/pio/dma? Used to prevent re-entrancy */
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MemReentrancyGuard mem_reentrancy_guard;
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};
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struct DeviceListener {
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@ -542,6 +542,18 @@ static MemTxResult access_with_adjusted_size(hwaddr addr,
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access_size_max = 4;
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}
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/* Do not allow more than one simultaneous access to a device's IO Regions */
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if (mr->dev && !mr->disable_reentrancy_guard &&
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!mr->ram_device && !mr->ram && !mr->rom_device && !mr->readonly) {
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if (mr->dev->mem_reentrancy_guard.engaged_in_io) {
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warn_report_once("Blocked re-entrant IO on MemoryRegion: "
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"%s at addr: 0x%" HWADDR_PRIX,
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memory_region_name(mr), addr);
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return MEMTX_ACCESS_ERROR;
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}
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mr->dev->mem_reentrancy_guard.engaged_in_io = true;
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}
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/* FIXME: support unaligned access? */
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access_size = MAX(MIN(size, access_size_max), access_size_min);
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access_mask = MAKE_64BIT_MASK(0, access_size * 8);
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@ -556,6 +568,9 @@ static MemTxResult access_with_adjusted_size(hwaddr addr,
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access_mask, attrs);
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}
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}
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if (mr->dev) {
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mr->dev->mem_reentrancy_guard.engaged_in_io = false;
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}
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return r;
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}
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@ -1170,6 +1185,7 @@ static void memory_region_do_init(MemoryRegion *mr,
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}
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mr->name = g_strdup(name);
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mr->owner = owner;
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mr->dev = (DeviceState *) object_dynamic_cast(mr->owner, TYPE_DEVICE);
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mr->ram_block = NULL;
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if (name) {
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