qemu-kvm/kvm-hw-scsi-lsi53c895a-Fix-reentrancy-issues-in-the-LSI-.patch

From 57a26ba1c4053cdc426653f921e66f7a8efd3ce7 Mon Sep 17 00:00:00 2001
From: Thomas Huth <thuth@redhat.com>
Date: Mon, 22 May 2023 11:10:11 +0200
Subject: [PATCH 12/15] hw/scsi/lsi53c895a: Fix reentrancy issues in the LSI
 controller (CVE-2023-0330)

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: [12/12] 28f5e04344109d8514869c50468bef481437201d (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 b987718bbb1d0eabf95499b976212dd5f0120d75
Author: Thomas Huth <thuth@redhat.com>
Date:   Mon May 22 11:10:11 2023 +0200

    hw/scsi/lsi53c895a: Fix reentrancy issues in the LSI controller (CVE-2023-0330)

    We cannot use the generic reentrancy guard in the LSI code, so
    we have to manually prevent endless reentrancy here. The problematic
    lsi_execute_script() function has already a way to detect whether
    too many instructions have been executed - we just have to slightly
    change the logic here that it also takes into account if the function
    has been called too often in a reentrant way.

    The code in fuzz-lsi53c895a-test.c has been taken from an earlier
    patch by Mauro Matteo Cascella.

    Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1563
    Message-Id: <20230522091011.1082574-1-thuth@redhat.com>
    Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
    Reviewed-by: Alexander Bulekov <alxndr@bu.edu>
    Signed-off-by: Thomas Huth <thuth@redhat.com>

Signed-off-by: Jon Maloy <jmaloy@redhat.com>
---
 hw/scsi/lsi53c895a.c               |  23 +++--
 tests/qtest/fuzz-lsi53c895a-test.c | 161 +++++++++++++++++++++++++++++
 2 files changed, 178 insertions(+), 6 deletions(-)
 create mode 100644 tests/qtest/fuzz-lsi53c895a-test.c

diff --git a/hw/scsi/lsi53c895a.c b/hw/scsi/lsi53c895a.c
index 2b9cb2ac5d..b60786fd56 100644
--- a/hw/scsi/lsi53c895a.c
+++ b/hw/scsi/lsi53c895a.c
@@ -1133,15 +1133,24 @@ static void lsi_execute_script(LSIState *s)
     uint32_t addr, addr_high;
     int opcode;
     int insn_processed = 0;
+    static int reentrancy_level;
+
+    reentrancy_level++;
 
     s->istat1 |= LSI_ISTAT1_SRUN;
 again:
-    if (++insn_processed > LSI_MAX_INSN) {
-        /* Some windows drivers make the device spin waiting for a memory
-           location to change.  If we have been executed a lot of code then
-           assume this is the case and force an unexpected device disconnect.
-           This is apparently sufficient to beat the drivers into submission.
-         */
+    /*
+     * Some windows drivers make the device spin waiting for a memory location
+     * to change. If we have executed more than LSI_MAX_INSN instructions then
+     * assume this is the case and force an unexpected device disconnect. This
+     * is apparently sufficient to beat the drivers into submission.
+     *
+     * Another issue (CVE-2023-0330) can occur if the script is programmed to
+     * trigger itself again and again. Avoid this problem by stopping after
+     * being called multiple times in a reentrant way (8 is an arbitrary value
+     * which should be enough for all valid use cases).
+     */
+    if (++insn_processed > LSI_MAX_INSN || reentrancy_level > 8) {
         if (!(s->sien0 & LSI_SIST0_UDC)) {
             qemu_log_mask(LOG_GUEST_ERROR,
                           "lsi_scsi: inf. loop with UDC masked");
@@ -1595,6 +1604,8 @@ again:
         }
     }
     trace_lsi_execute_script_stop();
+
+    reentrancy_level--;
 }
 
 static uint8_t lsi_reg_readb(LSIState *s, int offset)
diff --git a/tests/qtest/fuzz-lsi53c895a-test.c b/tests/qtest/fuzz-lsi53c895a-test.c
new file mode 100644
index 0000000000..1b55928b9f
--- /dev/null
+++ b/tests/qtest/fuzz-lsi53c895a-test.c
@@ -0,0 +1,161 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * QTest fuzzer-generated testcase for LSI53C895A device
+ *
+ * Copyright (c) Red Hat
+ */
+
+#include "qemu/osdep.h"
+#include "libqtest.h"
+
+/*
+ * This used to trigger a DMA reentrancy issue
+ * leading to memory corruption bugs like stack
+ * overflow or use-after-free
+ * https://gitlab.com/qemu-project/qemu/-/issues/1563
+ */
+static void test_lsi_dma_reentrancy(void)
+{
+    QTestState *s;
+
+    s = qtest_init("-M q35 -m 512M -nodefaults "
+                   "-blockdev driver=null-co,node-name=null0 "
+                   "-device lsi53c810 -device scsi-cd,drive=null0");
+
+    qtest_outl(s, 0xcf8, 0x80000804); /* PCI Command Register */
+    qtest_outw(s, 0xcfc, 0x7);        /* Enables accesses */
+    qtest_outl(s, 0xcf8, 0x80000814); /* Memory Bar 1 */
+    qtest_outl(s, 0xcfc, 0xff100000); /* Set MMIO Address*/
+    qtest_outl(s, 0xcf8, 0x80000818); /* Memory Bar 2 */
+    qtest_outl(s, 0xcfc, 0xff000000); /* Set RAM Address*/
+    qtest_writel(s, 0xff000000, 0xc0000024);
+    qtest_writel(s, 0xff000114, 0x00000080);
+    qtest_writel(s, 0xff00012c, 0xff000000);
+    qtest_writel(s, 0xff000004, 0xff000114);
+    qtest_writel(s, 0xff000008, 0xff100014);
+    qtest_writel(s, 0xff10002f, 0x000000ff);
+
+    qtest_quit(s);
+}
+
+/*
+ * This used to trigger a UAF in lsi_do_msgout()
+ * https://gitlab.com/qemu-project/qemu/-/issues/972
+ */
+static void test_lsi_do_msgout_cancel_req(void)
+{
+    QTestState *s;
+
+    if (sizeof(void *) == 4) {
+        g_test_skip("memory size too big for 32-bit build");
+        return;
+    }
+
+    s = qtest_init("-M q35 -m 2G -nodefaults "
+                   "-device lsi53c895a,id=scsi "
+                   "-device scsi-hd,drive=disk0 "
+                   "-drive file=null-co://,id=disk0,if=none,format=raw");
+
+    qtest_outl(s, 0xcf8, 0x80000810);
+    qtest_outl(s, 0xcf8, 0xc000);
+    qtest_outl(s, 0xcf8, 0x80000810);
+    qtest_outw(s, 0xcfc, 0x7);
+    qtest_outl(s, 0xcf8, 0x80000810);
+    qtest_outl(s, 0xcfc, 0xc000);
+    qtest_outl(s, 0xcf8, 0x80000804);
+    qtest_outw(s, 0xcfc, 0x05);
+    qtest_writeb(s, 0x69736c10, 0x08);
+    qtest_writeb(s, 0x69736c13, 0x58);
+    qtest_writeb(s, 0x69736c1a, 0x01);
+    qtest_writeb(s, 0x69736c1b, 0x06);
+    qtest_writeb(s, 0x69736c22, 0x01);
+    qtest_writeb(s, 0x69736c23, 0x07);
+    qtest_writeb(s, 0x69736c2b, 0x02);
+    qtest_writeb(s, 0x69736c48, 0x08);
+    qtest_writeb(s, 0x69736c4b, 0x58);
+    qtest_writeb(s, 0x69736c52, 0x04);
+    qtest_writeb(s, 0x69736c53, 0x06);
+    qtest_writeb(s, 0x69736c5b, 0x02);
+    qtest_outl(s, 0xc02d, 0x697300);
+    qtest_writeb(s, 0x5a554662, 0x01);
+    qtest_writeb(s, 0x5a554663, 0x07);
+    qtest_writeb(s, 0x5a55466a, 0x10);
+    qtest_writeb(s, 0x5a55466b, 0x22);
+    qtest_writeb(s, 0x5a55466c, 0x5a);
+    qtest_writeb(s, 0x5a55466d, 0x5a);
+    qtest_writeb(s, 0x5a55466e, 0x34);
+    qtest_writeb(s, 0x5a55466f, 0x5a);
+    qtest_writeb(s, 0x5a345a5a, 0x77);
+    qtest_writeb(s, 0x5a345a5b, 0x55);
+    qtest_writeb(s, 0x5a345a5c, 0x51);
+    qtest_writeb(s, 0x5a345a5d, 0x27);
+    qtest_writeb(s, 0x27515577, 0x41);
+    qtest_outl(s, 0xc02d, 0x5a5500);
+    qtest_writeb(s, 0x364001d0, 0x08);
+    qtest_writeb(s, 0x364001d3, 0x58);
+    qtest_writeb(s, 0x364001da, 0x01);
+    qtest_writeb(s, 0x364001db, 0x26);
+    qtest_writeb(s, 0x364001dc, 0x0d);
+    qtest_writeb(s, 0x364001dd, 0xae);
+    qtest_writeb(s, 0x364001de, 0x41);
+    qtest_writeb(s, 0x364001df, 0x5a);
+    qtest_writeb(s, 0x5a41ae0d, 0xf8);
+    qtest_writeb(s, 0x5a41ae0e, 0x36);
+    qtest_writeb(s, 0x5a41ae0f, 0xd7);
+    qtest_writeb(s, 0x5a41ae10, 0x36);
+    qtest_writeb(s, 0x36d736f8, 0x0c);
+    qtest_writeb(s, 0x36d736f9, 0x80);
+    qtest_writeb(s, 0x36d736fa, 0x0d);
+    qtest_outl(s, 0xc02d, 0x364000);
+
+    qtest_quit(s);
+}
+
+/*
+ * This used to trigger the assert in lsi_do_dma()
+ * https://bugs.launchpad.net/qemu/+bug/697510
+ * https://bugs.launchpad.net/qemu/+bug/1905521
+ * https://bugs.launchpad.net/qemu/+bug/1908515
+ */
+static void test_lsi_do_dma_empty_queue(void)
+{
+    QTestState *s;
+
+    s = qtest_init("-M q35 -nographic -monitor none -serial none "
+                   "-drive if=none,id=drive0,"
+                            "file=null-co://,file.read-zeroes=on,format=raw "
+                   "-device lsi53c895a,id=scsi0 "
+                   "-device scsi-hd,drive=drive0,"
+                            "bus=scsi0.0,channel=0,scsi-id=0,lun=0");
+    qtest_outl(s, 0xcf8, 0x80001814);
+    qtest_outl(s, 0xcfc, 0xe1068000);
+    qtest_outl(s, 0xcf8, 0x80001818);
+    qtest_outl(s, 0xcf8, 0x80001804);
+    qtest_outw(s, 0xcfc, 0x7);
+    qtest_outl(s, 0xcf8, 0x80002010);
+
+    qtest_writeb(s, 0xe106802e, 0xff); /* Fill DSP bits 16-23 */
+    qtest_writeb(s, 0xe106802f, 0xff); /* Fill DSP bits 24-31: trigger SCRIPT */
+
+    qtest_quit(s);
+}
+
+int main(int argc, char **argv)
+{
+    g_test_init(&argc, &argv, NULL);
+
+    if (!qtest_has_device("lsi53c895a")) {
+        return 0;
+    }
+
+    qtest_add_func("fuzz/lsi53c895a/lsi_do_dma_empty_queue",
+                   test_lsi_do_dma_empty_queue);
+
+    qtest_add_func("fuzz/lsi53c895a/lsi_do_msgout_cancel_req",
+                   test_lsi_do_msgout_cancel_req);
+
+    qtest_add_func("fuzz/lsi53c895a/lsi_dma_reentrancy",
+                   test_lsi_dma_reentrancy);
+
+    return g_test_run();
+}
-- 
2.37.3