qemu-kvm/SOURCES/kvm-memory-prevent-dma-reentracy-issues.patch
2023-11-07 09:43:59 +00:00

151 lines
5.1 KiB
Diff

From 0bc9295be331781491e993b6f1b0dca959194f13 Mon Sep 17 00:00:00 2001
From: Jon Maloy <jmaloy@redhat.com>
Date: Tue, 9 May 2023 10:29:03 -0400
Subject: [PATCH 05/21] memory: prevent dma-reentracy issues
RH-Author: Jon Maloy <jmaloy@redhat.com>
RH-MergeRequest: 165: memory: prevent dma-reentracy issues
RH-Jira: RHEL-516
RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>
RH-Commit: [1/13] d4a762d3b156200a65d09cde58cd6d77b229071e (jmaloy/jmaloy-qemu-kvm-2)
Jira: https://issues.redhat.com/browse/RHEL-516
Upstream: Merged
CVE: CVE-2023-2680
CVE: CVE-2023-0330
commit a2e1753b8054344f32cf94f31c6399a58794a380
Author: Alexander Bulekov <alxndr@bu.edu>
Date: Thu Apr 27 17:10:06 2023 -0400
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>
Signed-off-by: Jon Maloy <jmaloy@redhat.com>
---
include/exec/memory.h | 5 +++++
include/hw/qdev-core.h | 7 +++++++
softmmu/memory.c | 16 ++++++++++++++++
3 files changed, 28 insertions(+)
diff --git a/include/exec/memory.h b/include/exec/memory.h
index 15ade918ba..e45ce6061f 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -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 {
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 {
diff --git a/softmmu/memory.c b/softmmu/memory.c
index b1a6cae6f5..b7b3386e9d 100644
--- a/softmmu/memory.c
+++ b/softmmu/memory.c
@@ -542,6 +542,18 @@ static MemTxResult access_with_adjusted_size(hwaddr addr,
access_size_max = 4;
}
+ /* Do not allow more than one simultaneous access to a device's IO Regions */
+ if (mr->dev && !mr->disable_reentrancy_guard &&
+ !mr->ram_device && !mr->ram && !mr->rom_device && !mr->readonly) {
+ if (mr->dev->mem_reentrancy_guard.engaged_in_io) {
+ warn_report_once("Blocked re-entrant IO on MemoryRegion: "
+ "%s at addr: 0x%" HWADDR_PRIX,
+ memory_region_name(mr), addr);
+ return MEMTX_ACCESS_ERROR;
+ }
+ mr->dev->mem_reentrancy_guard.engaged_in_io = true;
+ }
+
/* FIXME: support unaligned access? */
access_size = MAX(MIN(size, access_size_max), access_size_min);
access_mask = MAKE_64BIT_MASK(0, access_size * 8);
@@ -556,6 +568,9 @@ static MemTxResult access_with_adjusted_size(hwaddr addr,
access_mask, attrs);
}
}
+ if (mr->dev) {
+ mr->dev->mem_reentrancy_guard.engaged_in_io = false;
+ }
return r;
}
@@ -1170,6 +1185,7 @@ static void memory_region_do_init(MemoryRegion *mr,
}
mr->name = g_strdup(name);
mr->owner = owner;
+ mr->dev = (DeviceState *) object_dynamic_cast(mr->owner, TYPE_DEVICE);
mr->ram_block = NULL;
if (name) {
--
2.39.3