References: bsc#980724 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: Li Qiang <address@hidden>
Signed-off-by: Prasad J Pandit <address@hidden>
---
hw/scsi/esp.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
Index: xen-4.7.0-testing/tools/qemu-xen-traditional-dir-remote/hw/esp.c
===================================================================
--- xen-4.7.0-testing.orig/tools/qemu-xen-traditional-dir-remote/hw/esp.c
+++ xen-4.7.0-testing/tools/qemu-xen-traditional-dir-remote/hw/esp.c
@@ -162,7 +162,7 @@ static void esp_lower_irq(ESPState *s)
}
}
-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;
@@ -170,6 +170,9 @@ static uint32_t get_cmd(ESPState *s, uin
target = s->wregs[ESP_WBUSID] & BUSID_DID;
if (s->dma) {
dmalen = s->rregs[ESP_TCLO] | (s->rregs[ESP_TCMID] << 8);
+ if (dmalen > buflen) {
+ return 0;
+ }
s->dma_memory_read(s->dma_opaque, buf, dmalen);
} else {
dmalen = s->ti_size;
@@ -231,14 +234,14 @@ static void handle_satn(ESPState *s)
uint8_t buf[32];
int len;
- len = get_cmd(s, buf);
+ len = get_cmd(s, buf, sizeof(buf));
if (len)
do_cmd(s, buf);
}
static void handle_satn_stop(ESPState *s)
{
- s->cmdlen = get_cmd(s, s->cmdbuf);
+ s->cmdlen = get_cmd(s, s->cmdbuf, sizeof(s->cmdbuf));
if (s->cmdlen) {
DPRINTF("Set ATN & Stop: cmdlen %d\n", s->cmdlen);
s->do_cmd = 1;