hw/scsi/lsi53c895a: add missing decrement of reentrancy counter

When the maximum count of SCRIPTS instructions is reached, the code
stops execution and returns, but fails to decrement the reentrancy
counter. This effectively renders the SCSI controller unusable
because on next entry the reentrancy counter is still above the limit.

This bug was seen on HP-UX 10.20 which seems to trigger SCRIPTS
loops.

Fixes: b987718bbb ("hw/scsi/lsi53c895a: Fix reentrancy issues in the LSI controller (CVE-2023-0330)")
Signed-off-by: Sven Schnelle <svens@stackframe.org>
Message-ID: <20240128202214.2644768-1-svens@stackframe.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Tested-by: Helge Deller <deller@gmx.de>
Signed-off-by: Thomas Huth <thuth@redhat.com>
(cherry picked from commit 8b09b7fe47082c69295a0fc0cc01b041b6385025)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

diff --git a/hw/scsi/lsi53c895a.c b/hw/scsi/lsi53c895a.c
index 634ed49c2e776222239e01cf5011de50fbe09f95..afbea0fefa441309a381f4cdc89c2db968126667 100644 (file)
--- a/hw/scsi/lsi53c895a.c
+++ b/hw/scsi/lsi53c895a.c
@@ -1159,6 +1159,7 @@ again:
         lsi_script_scsi_interrupt(s, LSI_SIST0_UDC, 0);
         lsi_disconnect(s);
         trace_lsi_execute_script_stop();
+        reentrancy_level--;
         return;
     }
     insn = read_dword(s, s->dsp);