From 61dbb7407999e27c2f3a048d22dc25e835fed6a3 Mon Sep 17 00:00:00 2001 From: Michael S. Tsirkin Date: Tue, 13 May 2014 08:03:34 -0500 Subject: [PATCH 16/20] virtio: validate num_sg when mapping RH-Author: Michael S. Tsirkin Message-id: <1399968167-29364-1-git-send-email-mst@redhat.com> Patchwork-id: 58812 O-Subject: [PATCH qemu-kvm RHEL6.6 v3 1/2] virtio: validate num_sg when mapping Bugzilla: 1096124 RH-Acked-by: Juan Quintela RH-Acked-by: Dr. David Alan Gilbert (git) RH-Acked-by: Stefan Hajnoczi RH-Acked-by: Xiao Wang CVE-2013-4535 CVE-2013-4536 Both virtio-block and virtio-serial read, VirtQueueElements are read in as buffers, and passed to virtqueue_map_sg(), where num_sg is taken from the wire and can force writes to indicies beyond VIRTQUEUE_MAX_SIZE. To fix, validate num_sg. Reported-by: Michael Roth Signed-off-by: Michael S. Tsirkin Cc: Amit Shah Signed-off-by: Juan Quintela (cherry picked from commit 36cf2a37132c7f01fa9adb5f95f5312b27742fd4) Conflicts: hw/virtio/virtio.c Bugzilla: 1096124 Tested: lightly on developer's box Brew build: http://brewweb.devel.redhat.com/brew/taskinfo?taskID=7440366 --- hw/virtio.c | 6 ++++++ 1 file changed, 6 insertions(+) Signed-off-by: Jeff E. Nelson --- hw/virtio.c | 6 ++++++ 1 files changed, 6 insertions(+), 0 deletions(-) diff --git a/hw/virtio.c b/hw/virtio.c index dc05365..d1f9974 100644 --- a/hw/virtio.c +++ b/hw/virtio.c @@ -424,6 +424,12 @@ void virtqueue_map_sg(struct iovec *sg, target_phys_addr_t *addr, unsigned int i; target_phys_addr_t len; + if (num_sg >= VIRTQUEUE_MAX_SIZE) { + error_report("virtio: map attempt out of bounds: %zd > %d", + num_sg, VIRTQUEUE_MAX_SIZE); + exit(1); + } + for (i = 0; i < num_sg; i++) { len = sg[i].iov_len; sg[i].iov_base = cpu_physical_memory_map(addr[i], &len, is_write); -- 1.7.1