Commit 6c1fef6b authored by Prasad J Pandit's avatar Prasad J Pandit Committed by Paolo Bonzini
Browse files

esp: check dma length before reading scsi command(CVE-2016-4441) 



The 53C9X Fast SCSI Controller(FSC) comes with an internal 16-byte
FIFO buffer. It is used to handle command and data transfer.
Routine get_cmd() uses DMA to read scsi commands into this buffer.
Add check to validate DMA length against buffer size to avoid any
overrun.

Fixes CVE-2016-4441.

Reported-by: default avatarLi Qiang <liqiang6-s@360.cn>
Cc: qemu-stable@nongnu.org
Signed-off-by: default avatarPrasad J Pandit <pjp@fedoraproject.org>
Message-Id: <1463654371-11169-3-git-send-email-ppandit@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent c98c6c10

hw/scsi/esp.c

+7 −4
Original line number Diff line number Diff line
@@ -82,7 +82,7 @@ void esp_request_cancelled(SCSIRequest *req) 
    }

}



static uint32_t get_cmd(ESPState *s, uint8_t *buf)

static uint32_t get_cmd(ESPState *s, uint8_t *buf, uint8_t buflen)

{

    uint32_t dmalen;

    int target;
@@ -92,6 +92,9 @@ static uint32_t get_cmd(ESPState *s, uint8_t *buf) 
        dmalen = s->rregs[ESP_TCLO];

        dmalen |= s->rregs[ESP_TCMID] << 8;

        dmalen |= s->rregs[ESP_TCHI] << 16;

        if (dmalen > buflen) {

            return 0;

        }

        s->dma_memory_read(s->dma_opaque, buf, dmalen);

    } else {

        dmalen = s->ti_size;
@@ -166,7 +169,7 @@ static void handle_satn(ESPState *s) 
        s->dma_cb = handle_satn;

        return;

    }

    len = get_cmd(s, buf);

    len = get_cmd(s, buf, sizeof(buf));

    if (len)

        do_cmd(s, buf);

}
@@ -180,7 +183,7 @@ static void handle_s_without_atn(ESPState *s) 
        s->dma_cb = handle_s_without_atn;

        return;

    }

    len = get_cmd(s, buf);

    len = get_cmd(s, buf, sizeof(buf));

    if (len) {

        do_busid_cmd(s, buf, 0);

    }
@@ -192,7 +195,7 @@ static void handle_satn_stop(ESPState *s) 
        s->dma_cb = handle_satn_stop;

        return;

    }

    s->cmdlen = get_cmd(s, s->cmdbuf);

    s->cmdlen = get_cmd(s, s->cmdbuf, sizeof(s->cmdbuf));

    if (s->cmdlen) {

        trace_esp_handle_satn_stop(s->cmdlen);

        s->do_cmd = 1;