From: Prasad J Pandit <p...@fedoraproject.org> 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 <liqiang...@360.cn> Cc: qemu-sta...@nongnu.org Signed-off-by: Prasad J Pandit <p...@fedoraproject.org> Message-Id: <1463654371-11169-3-git-send-email-ppan...@redhat.com> Signed-off-by: Paolo Bonzini <pbonz...@redhat.com> (cherry picked from commit 6c1fef6b59563cc415f21e03f81539ed4b33ad90) Signed-off-by: Michael Roth <mdr...@linux.vnet.ibm.com> --- 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; -- 1.9.1