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152 lines
5.2 KiB
152 lines
5.2 KiB
From e0c811c2d13f995fe1b095f48637316be5978b0e Mon Sep 17 00:00:00 2001
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From: Jon Maloy <jmaloy@redhat.com>
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Date: Tue, 9 May 2023 10:29:03 -0400
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Subject: [PATCH 01/15] memory: prevent dma-reentracy issues
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RH-Author: Jon Maloy <jmaloy@redhat.com>
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RH-MergeRequest: 277: memory: prevent dma-reentracy issues
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RH-Bugzilla: 1999236
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RH-Acked-by: Thomas Huth <thuth@redhat.com>
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RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>
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RH-Commit: [1/12] 8fced41b4b2105343e8f0250286b771bcb43c81f (redhat/rhel/src/qemu-kvm/jons-qemu-kvm-2)
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Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1999236
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Upstream: Merged
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CVE: CVE-2021-3750
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CVE: CVE-2023-0330
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commit a2e1753b8054344f32cf94f31c6399a58794a380
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Author: Alexander Bulekov <alxndr@bu.edu>
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Date: Thu Apr 27 17:10:06 2023 -0400
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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.
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This flag is set/checked prior to calling a device's MemoryRegion
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handlers, and set when device code initiates DMA. The purpose of this
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flag is to prevent two types of DMA-based reentrancy issues:
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1.) mmio -> dma -> mmio case
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2.) bh -> dma write -> mmio case
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These issues have led to problems such as stack-exhaustion and
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use-after-frees.
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Summary of the problem from Peter Maydell:
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https://lore.kernel.org/qemu-devel/CAFEAcA_23vc7hE3iaM-JVA6W38LK4hJoWae5KcknhPRD5fPBZA@mail.gmail.com
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Resolves: https://gitlab.com/qemu-project/qemu/-/issues/62
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Resolves: https://gitlab.com/qemu-project/qemu/-/issues/540
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Resolves: https://gitlab.com/qemu-project/qemu/-/issues/541
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Resolves: https://gitlab.com/qemu-project/qemu/-/issues/556
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Resolves: https://gitlab.com/qemu-project/qemu/-/issues/557
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Resolves: https://gitlab.com/qemu-project/qemu/-/issues/827
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Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1282
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Resolves: CVE-2023-0330
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Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
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Reviewed-by: Thomas Huth <thuth@redhat.com>
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Message-Id: <20230427211013.2994127-2-alxndr@bu.edu>
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[thuth: Replace warn_report() with warn_report_once()]
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Signed-off-by: Thomas Huth <thuth@redhat.com>
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Signed-off-by: Jon Maloy <jmaloy@redhat.com>
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---
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include/exec/memory.h | 5 +++++
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include/hw/qdev-core.h | 7 +++++++
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softmmu/memory.c | 16 ++++++++++++++++
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3 files changed, 28 insertions(+)
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diff --git a/include/exec/memory.h b/include/exec/memory.h
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index 20f1b27377..e089f90f9b 100644
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--- a/include/exec/memory.h
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+++ b/include/exec/memory.h
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@@ -734,6 +734,8 @@ 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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@@ -757,6 +759,9 @@ 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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+
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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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diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
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index 20d3066595..14226f860d 100644
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--- a/include/hw/qdev-core.h
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+++ b/include/hw/qdev-core.h
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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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/**
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* DeviceState:
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* @realized: Indicates whether the device has been fully constructed.
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@@ -193,6 +197,9 @@ struct DeviceState {
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int instance_id_alias;
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int alias_required_for_version;
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ResettableState reset;
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+
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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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diff --git a/softmmu/memory.c b/softmmu/memory.c
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index 7340e19ff5..102f0a4248 100644
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--- a/softmmu/memory.c
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+++ b/softmmu/memory.c
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@@ -541,6 +541,18 @@ 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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+
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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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@@ -555,6 +567,9 @@ 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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@@ -1169,6 +1184,7 @@ 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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--
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2.37.3
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