diff options
author | Gerd Hoffmann <kraxel@redhat.com> | 2020-08-25 07:36:36 +0200 |
---|---|---|
committer | Michael Roth <mdroth@linux.vnet.ibm.com> | 2020-09-09 18:51:39 -0500 |
commit | f243bb4b0d6dab7da3ae8490e0f46054bae93816 (patch) | |
tree | 2a95485a7a83e25d626f7a13b086336d1e66faef | |
parent | a575af07b8009bc51a311274c15846697b7d5f7c (diff) | |
download | qemu-f243bb4b0d6dab7da3ae8490e0f46054bae93816.zip qemu-f243bb4b0d6dab7da3ae8490e0f46054bae93816.tar.gz qemu-f243bb4b0d6dab7da3ae8490e0f46054bae93816.tar.bz2 |
usb: fix setup_len init (CVE-2020-14364)
Store calculated setup_len in a local variable, verify it, and only
write it to the struct (USBDevice->setup_len) in case it passed the
sanity checks.
This prevents other code (do_token_{in,out} functions specifically)
from working with invalid USBDevice->setup_len values and overrunning
the USBDevice->setup_buf[] buffer.
Fixes: CVE-2020-14364
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Tested-by: Gonglei <arei.gonglei@huawei.com>
Reviewed-by: Li Qiang <liq3ea@gmail.com>
Message-id: 20200825053636.29648-1-kraxel@redhat.com
(cherry picked from commit b946434f2659a182afc17e155be6791ebfb302eb)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
-rw-r--r-- | hw/usb/core.c | 16 |
1 files changed, 10 insertions, 6 deletions
diff --git a/hw/usb/core.c b/hw/usb/core.c index 5abd128..5234dcc 100644 --- a/hw/usb/core.c +++ b/hw/usb/core.c @@ -129,6 +129,7 @@ void usb_wakeup(USBEndpoint *ep, unsigned int stream) static void do_token_setup(USBDevice *s, USBPacket *p) { int request, value, index; + unsigned int setup_len; if (p->iov.size != 8) { p->status = USB_RET_STALL; @@ -138,14 +139,15 @@ static void do_token_setup(USBDevice *s, USBPacket *p) usb_packet_copy(p, s->setup_buf, p->iov.size); s->setup_index = 0; p->actual_length = 0; - s->setup_len = (s->setup_buf[7] << 8) | s->setup_buf[6]; - if (s->setup_len > sizeof(s->data_buf)) { + setup_len = (s->setup_buf[7] << 8) | s->setup_buf[6]; + if (setup_len > sizeof(s->data_buf)) { fprintf(stderr, "usb_generic_handle_packet: ctrl buffer too small (%d > %zu)\n", - s->setup_len, sizeof(s->data_buf)); + setup_len, sizeof(s->data_buf)); p->status = USB_RET_STALL; return; } + s->setup_len = setup_len; request = (s->setup_buf[0] << 8) | s->setup_buf[1]; value = (s->setup_buf[3] << 8) | s->setup_buf[2]; @@ -259,26 +261,28 @@ static void do_token_out(USBDevice *s, USBPacket *p) static void do_parameter(USBDevice *s, USBPacket *p) { int i, request, value, index; + unsigned int setup_len; for (i = 0; i < 8; i++) { s->setup_buf[i] = p->parameter >> (i*8); } s->setup_state = SETUP_STATE_PARAM; - s->setup_len = (s->setup_buf[7] << 8) | s->setup_buf[6]; s->setup_index = 0; request = (s->setup_buf[0] << 8) | s->setup_buf[1]; value = (s->setup_buf[3] << 8) | s->setup_buf[2]; index = (s->setup_buf[5] << 8) | s->setup_buf[4]; - if (s->setup_len > sizeof(s->data_buf)) { + setup_len = (s->setup_buf[7] << 8) | s->setup_buf[6]; + if (setup_len > sizeof(s->data_buf)) { fprintf(stderr, "usb_generic_handle_packet: ctrl buffer too small (%d > %zu)\n", - s->setup_len, sizeof(s->data_buf)); + setup_len, sizeof(s->data_buf)); p->status = USB_RET_STALL; return; } + s->setup_len = setup_len; if (p->pid == USB_TOKEN_OUT) { usb_packet_copy(p, s->data_buf, s->setup_len); |