qemu-kvm/kvm-async-avoid-use-after-free-on-re-entrancy-guard.patch
Jon Maloy fc2ddd6b1c * Thu Jun 29 2023 Jon Maloy <jmaloy@redhat.com> - 6.2.0-36
- kvm-memory-prevent-dma-reentracy-issues.patch [bz#1999236]
- kvm-async-Add-an-optional-reentrancy-guard-to-the-BH-API.patch [bz#1999236]
- kvm-checkpatch-add-qemu_bh_new-aio_bh_new-checks.patch [bz#1999236]
- kvm-hw-replace-most-qemu_bh_new-calls-with-qemu_bh_new_g.patch [bz#1999236]
- kvm-lsi53c895a-disable-reentrancy-detection-for-script-R.patch [bz#1999236]
- kvm-bcm2835_property-disable-reentrancy-detection-for-io.patch [bz#1999236]
- kvm-raven-disable-reentrancy-detection-for-iomem.patch [bz#1999236]
- kvm-apic-disable-reentrancy-detection-for-apic-msi.patch [bz#1999236]
- kvm-async-avoid-use-after-free-on-re-entrancy-guard.patch [bz#1999236]
- kvm-memory-stricter-checks-prior-to-unsetting-engaged_in.patch [bz#1999236]
- kvm-lsi53c895a-disable-reentrancy-detection-for-MMIO-reg.patch [bz#1999236]
- kvm-hw-scsi-lsi53c895a-Fix-reentrancy-issues-in-the-LSI-.patch [bz#1999236]
- kvm-target-i386-add-support-for-FLUSH_L1D-feature.patch [bz#2216203]
- kvm-target-i386-add-support-for-FB_CLEAR-feature.patch [bz#2216203]
- kvm-migration-Disable-postcopy-multifd-migration.patch [bz#2169733]
- Resolves: bz#1999236
  (CVE-2021-3750 virt:rhel/qemu-kvm: QEMU: hcd-ehci: DMA reentrancy issue leads to use-after-free [rhel-8])
- Resolves: bz#2216203
  ([qemu-kvm]VM reports vulnerabilty to mmio_stale_data on patched host with microcode)
- Resolves: bz#2169733
  (Qemu on destination host crashed if migrate with postcopy and multifd enabled)
2023-06-29 21:05:35 +00:00

72 lines
2.5 KiB
Diff

From d754050d260e2ad890cecd975df6e163c531b40e Mon Sep 17 00:00:00 2001
From: Jon Maloy <jmaloy@redhat.com>
Date: Tue, 9 May 2023 10:29:03 -0400
Subject: [PATCH 09/15] async: avoid use-after-free on re-entrancy guard
RH-Author: Jon Maloy <jmaloy@redhat.com>
RH-MergeRequest: 277: memory: prevent dma-reentracy issues
RH-Bugzilla: 1999236
RH-Acked-by: Thomas Huth <thuth@redhat.com>
RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>
RH-Commit: [9/12] d357650e581c3921bbfe3e2fde5e3f55853b5fab (redhat/rhel/src/qemu-kvm/jons-qemu-kvm-2)
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1999236
Upstream: Merged
CVE: CVE-2021-3750
commit 7915bd06f25e1803778081161bf6fa10c42dc7cd
Author: Alexander Bulekov <alxndr@bu.edu>
Date: Mon May 1 10:19:56 2023 -0400
async: avoid use-after-free on re-entrancy guard
A BH callback can free the BH, causing a use-after-free in aio_bh_call.
Fix that by keeping a local copy of the re-entrancy guard pointer.
Buglink: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=58513
Fixes: 9c86c97f12 ("async: Add an optional reentrancy guard to the BH API")
Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
Message-Id: <20230501141956.3444868-1-alxndr@bu.edu>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Jon Maloy <jmaloy@redhat.com>
---
util/async.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)
diff --git a/util/async.c b/util/async.c
index 1fff02e7fc..ffe0541c3b 100644
--- a/util/async.c
+++ b/util/async.c
@@ -146,18 +146,20 @@ void aio_bh_call(QEMUBH *bh)
{
bool last_engaged_in_io = false;
- if (bh->reentrancy_guard) {
- last_engaged_in_io = bh->reentrancy_guard->engaged_in_io;
- if (bh->reentrancy_guard->engaged_in_io) {
+ /* Make a copy of the guard-pointer as cb may free the bh */
+ MemReentrancyGuard *reentrancy_guard = bh->reentrancy_guard;
+ if (reentrancy_guard) {
+ last_engaged_in_io = reentrancy_guard->engaged_in_io;
+ if (reentrancy_guard->engaged_in_io) {
trace_reentrant_aio(bh->ctx, bh->name);
}
- bh->reentrancy_guard->engaged_in_io = true;
+ reentrancy_guard->engaged_in_io = true;
}
bh->cb(bh->opaque);
- if (bh->reentrancy_guard) {
- bh->reentrancy_guard->engaged_in_io = last_engaged_in_io;
+ if (reentrancy_guard) {
+ reentrancy_guard->engaged_in_io = last_engaged_in_io;
}
}
--
2.37.3