From 9330e486e884f1757d6920a25c6cc491eedad0d0 Mon Sep 17 00:00:00 2001 From: Jon Maloy Date: Fri, 4 Sep 2020 16:09:13 -0400 Subject: [PATCH 3/3] usb: fix setup_len init (CVE-2020-14364) RH-Author: Jon Maloy Message-id: <20200904160913.87759-3-jmaloy@redhat.com> Patchwork-id: 98291 O-Subject: [RHEL-7.9 qemu-kvm PATCH 2/2] usb: fix setup_len init (CVE-2020-14364) Bugzilla: 1869693 RH-Acked-by: Dr. David Alan Gilbert RH-Acked-by: Gerd Hoffmann RH-Acked-by: Thomas Huth From: Gerd Hoffmann 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 Tested-by: Gonglei Reviewed-by: Li Qiang Message-id: 20200825053636.29648-1-kraxel@redhat.com (cherry picked from commit b946434f2659a182afc17e155be6791ebfb302eb) Signed-off-by: Jon Maloy Signed-off-by: Jon Maloy --- hw/usb/core.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) diff --git a/hw/usb/core.c b/hw/usb/core.c index f0201e30b4..f0038e44ae 100644 --- a/hw/usb/core.c +++ b/hw/usb/core.c @@ -121,6 +121,7 @@ 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; @@ -130,14 +131,15 @@ 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]; @@ -251,26 +253,28 @@ 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); -- 2.18.2