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Re: [Qemu-devel] [PATCH v3] scsi: esp: check TI buffer index before read
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH v3] scsi: esp: check TI buffer index before read/write |
Date: |
Mon, 6 Jun 2016 18:57:27 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.1.0 |
On 06/06/2016 18:34, P J P wrote:
> From: Prasad J Pandit <address@hidden>
>
> The 53C9X Fast SCSI Controller(FSC) comes with internal 16-byte
> FIFO buffers. One is used to handle commands and other is for
> information transfer. Three control variables 'ti_rptr',
> 'ti_wptr' and 'ti_size' are used to control r/w access to the
> information transfer buffer ti_buf[TI_BUFSZ=16]. In that,
>
> 'ti_rptr' is used as read index, where read occurs.
> 'ti_wptr' is a write index, where write would occur.
> 'ti_size' indicates total bytes to be read from the buffer.
>
> While reading/writing to this buffer, index could exceed its
> size. Add check to avoid OOB r/w access.
>
> Reported-by: Huawei PSIRT <address@hidden>
> Reported-by: Li Qiang <address@hidden>
> Signed-off-by: Prasad J Pandit <address@hidden>
> ---
> hw/scsi/esp.c | 20 +++++++++-----------
> 1 file changed, 9 insertions(+), 11 deletions(-)
>
> Update as per:
> -> https://lists.gnu.org/archive/html/qemu-devel/2016-06/msg01326.html
>
> diff --git a/hw/scsi/esp.c b/hw/scsi/esp.c
> index c2f6f8f..4b94bbc 100644
> --- a/hw/scsi/esp.c
> +++ b/hw/scsi/esp.c
> @@ -403,19 +403,17 @@ uint64_t esp_reg_read(ESPState *s, uint32_t saddr)
> trace_esp_mem_readb(saddr, s->rregs[saddr]);
> switch (saddr) {
> case ESP_FIFO:
> - if (s->ti_size > 0) {
> + if ((s->rregs[ESP_RSTAT] & STAT_PIO_MASK) == 0) {
> + /* Data out. */
> + qemu_log_mask(LOG_UNIMP, "esp: PIO data read not implemented\n");
> + s->rregs[ESP_FIFO] = 0;
> + esp_raise_irq(s);
> + } else if (s->ti_rptr < s->ti_wptr) {
> s->ti_size--;
> - if ((s->rregs[ESP_RSTAT] & STAT_PIO_MASK) == 0) {
> - /* Data out. */
> - qemu_log_mask(LOG_UNIMP,
> - "esp: PIO data read not implemented\n");
> - s->rregs[ESP_FIFO] = 0;
> - } else {
> - s->rregs[ESP_FIFO] = s->ti_buf[s->ti_rptr++];
> - }
> + s->rregs[ESP_FIFO] = s->ti_buf[s->ti_rptr++];
> esp_raise_irq(s);
> }
> - if (s->ti_size == 0) {
> + if (s->ti_rptr == s->ti_wptr) {
> s->ti_rptr = 0;
> s->ti_wptr = 0;
> }
> @@ -459,7 +457,7 @@ void esp_reg_write(ESPState *s, uint32_t saddr, uint64_t
> val)
> } else {
> trace_esp_error_fifo_overrun();
> }
> - } else if (s->ti_size == TI_BUFSZ - 1) {
> + } else if (s->ti_wptr == TI_BUFSZ - 1) {
> trace_esp_error_fifo_overrun();
> } else {
> s->ti_size++;
>
Queued, thanks.
Paolo