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qemu-kvm/SOURCES/kvm-memory-stricter-checks-...

68 lines
2.2 KiB

From 3f2042e33acb6db91594e12ebd63b9abd9e753cc Mon Sep 17 00:00:00 2001
From: Jon Maloy <jmaloy@redhat.com>
Date: Wed, 7 Jun 2023 11:45:09 -0400
Subject: [PATCH 15/21] memory: stricter checks prior to unsetting
engaged_in_io
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: [11/13] b8e1a4b49dd7fa3b7948d32f46dfe1d7f7a4c1cf (jmaloy/jmaloy-qemu-kvm-2)
Jira: https://issues.redhat.com/browse/RHEL-516
Upstream: Merged
CVE: CVE-2023-2680
commit 3884bf6468ac6bbb58c2b3feaa74e87f821b52f3
Author: Alexander Bulekov <alxndr@bu.edu>
Date: Tue May 16 04:40:02 2023 -0400
memory: stricter checks prior to unsetting engaged_in_io
engaged_in_io could be unset by an MR with re-entrancy checks disabled.
Ensure that only MRs that can set the engaged_in_io flag can unset it.
Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
Message-Id: <20230516084002.3813836-1-alxndr@bu.edu>
Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Jon Maloy <jmaloy@redhat.com>
---
softmmu/memory.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/softmmu/memory.c b/softmmu/memory.c
index b7b3386e9d..26424f1d78 100644
--- a/softmmu/memory.c
+++ b/softmmu/memory.c
@@ -534,6 +534,7 @@ static MemTxResult access_with_adjusted_size(hwaddr addr,
unsigned access_size;
unsigned i;
MemTxResult r = MEMTX_OK;
+ bool reentrancy_guard_applied = false;
if (!access_size_min) {
access_size_min = 1;
@@ -552,6 +553,7 @@ static MemTxResult access_with_adjusted_size(hwaddr addr,
return MEMTX_ACCESS_ERROR;
}
mr->dev->mem_reentrancy_guard.engaged_in_io = true;
+ reentrancy_guard_applied = true;
}
/* FIXME: support unaligned access? */
@@ -568,7 +570,7 @@ static MemTxResult access_with_adjusted_size(hwaddr addr,
access_mask, attrs);
}
}
- if (mr->dev) {
+ if (mr->dev && reentrancy_guard_applied) {
mr->dev->mem_reentrancy_guard.engaged_in_io = false;
}
return r;
--
2.39.3