[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 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 Reviewed-by: Alexander Bulekov Signed-off-by: Thomas Huth Reference: https://launchpad.net/ubuntu/+source/qemu/1:4.2-3ubuntu6.27 Upstream-Status: Backport [import from ubuntu https://git.launchpad.net/ubuntu/+source/qemu/tree/debian/patches/CVE-2023-0330.patch?h=ubuntu/focal-security Upstream commit https://gitlab.com/qemu-project/qemu/-/commit/b987718bbb1d0eabf95499b976212dd5f0120d75] CVE: CVE-2023-0330 Signed-off-by: Vijay Anusuri --- hw/scsi/lsi53c895a.c | 23 +++++++++++++++------ tests/qtest/fuzz-lsi53c895a-test.c | 33 ++++++++++++++++++++++++++++++ 2 files changed, 50 insertions(+), 6 deletions(-) --- qemu-4.2.orig/hw/scsi/lsi53c895a.c +++ qemu-4.2/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)