From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37708) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1b4rUx-0002MO-4C for qemu-devel@nongnu.org; Mon, 23 May 2016 11:10:28 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1b4rUs-00048O-4S for qemu-devel@nongnu.org; Mon, 23 May 2016 11:10:26 -0400 Sender: Paolo Bonzini From: Paolo Bonzini Date: Mon, 23 May 2016 17:09:54 +0200 Message-Id: <1464016199-43768-20-git-send-email-pbonzini@redhat.com> In-Reply-To: <1464016199-43768-1-git-send-email-pbonzini@redhat.com> References: <1464016199-43768-1-git-send-email-pbonzini@redhat.com> Subject: [Qemu-devel] [PULL 19/24] esp: check dma length before reading scsi command(CVE-2016-4441) List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Prasad J Pandit , qemu-stable@nongnu.org From: Prasad J Pandit 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: Li Qiang Cc: qemu-stable@nongnu.org Signed-off-by: Prasad J Pandit Message-Id: <1463654371-11169-3-git-send-email-ppandit@redhat.com> Signed-off-by: Paolo Bonzini --- hw/scsi/esp.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/hw/scsi/esp.c b/hw/scsi/esp.c index 01497e6..591c817 100644 --- a/hw/scsi/esp.c +++ b/hw/scsi/esp.c @@ -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; -- 1.8.3.1