diff options
authorMichael S. Tsirkin <mst@redhat.com>2016-04-18 13:07:35 +0300
committerPeter Maydell <peter.maydell@linaro.org>2016-04-19 11:13:59 +0100
commit5eb0b194e9b01ba0f3613e6ddc2cb9f63ce96ae5 (patch)
parenta087cc589d3581a89fdb8c09324941512b5ef300 (diff)
cadence_uart: bounds check write offset
cadence_uart_init() initializes an I/O memory region of size 0x1000 bytes. However in uart_write(), the 'offset' parameter (offset within region) is divided by 4 and then used to index the array 'r' of size CADENCE_UART_R_MAX which is much smaller: (0x48/4). If 'offset>>=2' exceeds CADENCE_UART_R_MAX, this will cause an out-of-bounds memory write where the offset and the value are controlled by guest. This will corrupt QEMU memory, in most situations this causes the vm to crash. Fix by checking the offset against the array size. Cc: qemu-stable@nongnu.org Reported-by: 李强 <liqiang6-s@360.cn> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Reviewed-by: Alistair Francis <alistair.francis@xilinx.com> Message-id: 20160418100735.GA517@redhat.com Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
1 files changed, 3 insertions, 0 deletions
diff --git a/hw/char/cadence_uart.c b/hw/char/cadence_uart.c
index 486591bf07..797787823e 100644
--- a/hw/char/cadence_uart.c
+++ b/hw/char/cadence_uart.c
@@ -375,6 +375,9 @@ static void uart_write(void *opaque, hwaddr offset,
DB_PRINT(" offset:%x data:%08x\n", (unsigned)offset, (unsigned)value);
offset >>= 2;
+ if (offset >= CADENCE_UART_R_MAX) {
+ return;
+ }
switch (offset) {
case R_IER: /* ier (wts imr) */
s->r[R_IMR] |= value;