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69 lines
2.3 KiB
69 lines
2.3 KiB
1 year ago
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From c24e38eb508b3fb42ce3ea62fe8de0be6a95a6a8 Mon Sep 17 00:00:00 2001
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From: Jon Maloy <jmaloy@redhat.com>
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Date: Wed, 7 Jun 2023 11:45:09 -0400
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Subject: [PATCH 10/15] memory: stricter checks prior to unsetting
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engaged_in_io
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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: [10/12] 773b62a84b2bd4f5ee7fb8e1cfb3bb91c3a01de1 (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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commit 3884bf6468ac6bbb58c2b3feaa74e87f821b52f3
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Author: Alexander Bulekov <alxndr@bu.edu>
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Date: Tue May 16 04:40:02 2023 -0400
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memory: stricter checks prior to unsetting engaged_in_io
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engaged_in_io could be unset by an MR with re-entrancy checks disabled.
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Ensure that only MRs that can set the engaged_in_io flag can unset it.
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Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
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Message-Id: <20230516084002.3813836-1-alxndr@bu.edu>
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Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
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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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softmmu/memory.c | 4 +++-
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1 file changed, 3 insertions(+), 1 deletion(-)
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diff --git a/softmmu/memory.c b/softmmu/memory.c
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index 102f0a4248..6b98615357 100644
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--- a/softmmu/memory.c
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+++ b/softmmu/memory.c
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@@ -533,6 +533,7 @@ static MemTxResult access_with_adjusted_size(hwaddr addr,
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unsigned access_size;
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unsigned i;
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MemTxResult r = MEMTX_OK;
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+ bool reentrancy_guard_applied = false;
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if (!access_size_min) {
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access_size_min = 1;
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@@ -551,6 +552,7 @@ static MemTxResult access_with_adjusted_size(hwaddr 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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+ reentrancy_guard_applied = true;
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}
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/* FIXME: support unaligned access? */
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@@ -567,7 +569,7 @@ 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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+ if (mr->dev && reentrancy_guard_applied) {
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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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2.37.3
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