esp: check for NULL result from scsi_device_find()

Add a 'current_lun' check for a null value
to avoid null pointer dereferencing and
recover host if NULL return

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 4eb8606560 (esp: store lun coming from the MESSAGE OUT phase)
Signed-off-by: Alexandra Diupina <adiupina@astralinux.ru>
Message-ID: <20231229152647.19699-1-adiupina@astralinux.ru>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/hw/scsi/esp.c b/hw/scsi/esp.c
index 9b11d8c5738ab34a3fbf62c4bcaa0b3cea84c4af..d2cae79194c0085350604ffb60ac9184629bcaeb 100644 (file)
--- a/hw/scsi/esp.c
+++ b/hw/scsi/esp.c
@@ -292,6 +292,15 @@ static void do_command_phase(ESPState *s)
     esp_fifo_pop_buf(&s->cmdfifo, buf, cmdlen);
 
     current_lun = scsi_device_find(&s->bus, 0, s->current_dev->id, s->lun);
+    if (!current_lun) {
+        /* No such drive */
+        s->rregs[ESP_RSTAT] = 0;
+        s->rregs[ESP_RINTR] = INTR_DC;
+        s->rregs[ESP_RSEQ] = SEQ_0;
+        esp_raise_irq(s);
+        return;
+    }
+
     s->current_req = scsi_req_new(current_lun, 0, s->lun, buf, cmdlen, s);
     datalen = scsi_req_enqueue(s->current_req);
     s->ti_size = datalen;