[PATCH] scsi/lsi53c895a: restrict DMA engine to memory regions (CVE-2023-0330)

[Mauro Matteo Cascella]

This prevents the well known DMA-MMIO reentrancy problem (upstream issue #556)
leading to memory corruption bugs like stack overflow or use-after-free.

Fixes: CVE-2023-0330
Signed-off-by: Mauro Matteo Cascella <mcascell@redhat.com>
Reported-by: Zheyu Ma <zheyuma97@gmail.com>
---
 hw/scsi/lsi53c895a.c               | 14 +++++++++----
 tests/qtest/fuzz-lsi53c895a-test.c | 32 ++++++++++++++++++++++++++++++
 2 files changed, 42 insertions(+), 4 deletions(-)

diff --git a/hw/scsi/lsi53c895a.c b/hw/scsi/lsi53c895a.c
index af93557a9a..89c52594eb 100644
--- a/hw/scsi/lsi53c895a.c
+++ b/hw/scsi/lsi53c895a.c
@@ -446,22 +446,28 @@ static void lsi_reselect(LSIState *s, lsi_request *p);
 static inline void lsi_mem_read(LSIState *s, dma_addr_t addr,
                                void *buf, dma_addr_t len)
 {
+    const MemTxAttrs attrs = { .memory = true };
+
     if (s->dmode & LSI_DMODE_SIOM) {
-        address_space_read(&s->pci_io_as, addr, MEMTXATTRS_UNSPECIFIED,
+        address_space_read(&s->pci_io_as, addr, attrs,
                            buf, len);
     } else {
-        pci_dma_read(PCI_DEVICE(s), addr, buf, len);
+        pci_dma_rw(PCI_DEVICE(s), addr, buf, len,
+                      DMA_DIRECTION_TO_DEVICE, attrs);
     }
 }
 
 static inline void lsi_mem_write(LSIState *s, dma_addr_t addr,
                                 const void *buf, dma_addr_t len)
 {
+    const MemTxAttrs attrs = { .memory = true };
+
     if (s->dmode & LSI_DMODE_DIOM) {
-        address_space_write(&s->pci_io_as, addr, MEMTXATTRS_UNSPECIFIED,
+        address_space_write(&s->pci_io_as, addr, attrs,
                             buf, len);
     } else {
-        pci_dma_write(PCI_DEVICE(s), addr, buf, len);
+        pci_dma_rw(PCI_DEVICE(s), addr, (void *) buf, len,
+                      DMA_DIRECTION_FROM_DEVICE, attrs);
     }
 }
 
diff --git a/tests/qtest/fuzz-lsi53c895a-test.c 
b/tests/qtest/fuzz-lsi53c895a-test.c
index 392a7ae7ed..35c02e89f3 100644
--- a/tests/qtest/fuzz-lsi53c895a-test.c
+++ b/tests/qtest/fuzz-lsi53c895a-test.c
@@ -8,6 +8,35 @@
 #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
+ */
+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
@@ -120,5 +149,8 @@ int main(int argc, char **argv)
     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();
 }
-- 
2.39.0