[v2] esp: process the result of scsi_device_find()

Commit Message

Alexandra Diupina Dec. 29, 2023, 3:26 p.m. UTC

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 <[e-mail]>
---
v2: duplicate the scsi_device_find() logic from esp_select()
 hw/scsi/esp.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

Comments

Philippe Mathieu-Daudé Dec. 29, 2023, 5:51 p.m. UTC | #1

Cc'ing Mark.

On 29/12/23 16:26, Alexandra Diupina wrote:
> 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 <[e-mail]>
> ---
> v2: duplicate the scsi_device_find() logic from esp_select()
>   hw/scsi/esp.c | 10 ++++++++++
>   1 file changed, 10 insertions(+)
> 
> diff --git a/hw/scsi/esp.c b/hw/scsi/esp.c
> index 9b11d8c573..03fdd53de6 100644
> --- a/hw/scsi/esp.c
> +++ b/hw/scsi/esp.c
> @@ -292,6 +292,16 @@ 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;

Paolo Bonzini Dec. 30, 2023, 9:32 a.m. UTC | #2

Queued, thanks.

Paolo

Patch

diff --git a/hw/scsi/esp.c b/hw/scsi/esp.c
index 9b11d8c573..03fdd53de6 100644
--- a/hw/scsi/esp.c
+++ b/hw/scsi/esp.c
@@ -292,6 +292,16 @@  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;