[Ubuntu note: remove fuzz-lsi53c895a-test.c changes since the file does not
 exist for this release]
From b987718bbb1d0eabf95499b976212dd5f0120d75 Mon Sep 17 00:00:00 2001
From: Thomas Huth <thuth@redhat.com>
Date: Mon, 22 May 2023 11:10:11 +0200
Subject: [PATCH] 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>

Upstream-Status: Backport [import from ubuntu https://git.launchpad.net/ubuntu/+source/qemu/tree/debian/patches/CVE-2023-0330.patch?h=ubuntu/jammy-security
Upstream commit https://gitlab.com/qemu-project/qemu/-/commit/b987718bbb1d0eabf95499b976212dd5f0120d75]
CVE: CVE-2023-0330
Signed-off-by: Vijay Anusuri <vanusuri@mvista.com>
---
 hw/scsi/lsi53c895a.c               | 23 +++++++++++++++------
 tests/qtest/fuzz-lsi53c895a-test.c | 33 ++++++++++++++++++++++++++++++
 2 files changed, 50 insertions(+), 6 deletions(-)

--- qemu-6.2+dfsg.orig/hw/scsi/lsi53c895a.c
+++ qemu-6.2+dfsg/hw/scsi/lsi53c895a.c
@@ -1135,15 +1135,24 @@ static void lsi_execute_script(LSIState
     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");
@@ -1597,6 +1606,8 @@ again:
         }
     }
     trace_lsi_execute_script_stop();
+
+    reentrancy_level--;
 }
 
 static uint8_t lsi_reg_readb(LSIState *s, int offset)
