From 780e83c259fc33e8959fed8dfdad17e378d72b62 Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Tue, 25 Sep 2018 02:12:30 -0600 Subject: [PATCH] xen-netback: fix input validation in xenvif_set_hash_mapping() Both len and off are frontend specified values, so we need to make sure there's no overflow when adding the two for the bounds check. We also want to avoid undefined behavior and hence use off to index into ->hash.mapping[] only after bounds checking. This at the same time allows to take care of not applying off twice for the bounds checking against vif->num_queues. It is also insufficient to bounds check copy_op.len, as this is len truncated to 16 bits. This is XSA-270 / CVE-2018-15471. Reported-by: Felix Wilhelm Signed-off-by: Jan Beulich Reviewed-by: Paul Durrant Tested-by: Paul Durrant Cc: stable@vger.kernel.org [4.7 onwards] Signed-off-by: David S. Miller --- drivers/net/xen-netback/hash.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/drivers/net/xen-netback/hash.c b/drivers/net/xen-netback/hash.c index 3c4c58b9fe76..3b6fb5b3bdb2 100644 --- a/drivers/net/xen-netback/hash.c +++ b/drivers/net/xen-netback/hash.c @@ -332,20 +332,22 @@ u32 xenvif_set_hash_mapping_size(struct xenvif *vif, u32 size) u32 xenvif_set_hash_mapping(struct xenvif *vif, u32 gref, u32 len, u32 off) { - u32 *mapping = &vif->hash.mapping[off]; + u32 *mapping = vif->hash.mapping; struct gnttab_copy copy_op = { .source.u.ref = gref, .source.domid = vif->domid, - .dest.u.gmfn = virt_to_gfn(mapping), .dest.domid = DOMID_SELF, - .dest.offset = xen_offset_in_page(mapping), - .len = len * sizeof(u32), + .len = len * sizeof(*mapping), .flags = GNTCOPY_source_gref }; - if ((off + len > vif->hash.size) || copy_op.len > XEN_PAGE_SIZE) + if ((off + len < off) || (off + len > vif->hash.size) || + len > XEN_PAGE_SIZE / sizeof(*mapping)) return XEN_NETIF_CTRL_STATUS_INVALID_PARAMETER; + copy_op.dest.u.gmfn = virt_to_gfn(mapping + off); + copy_op.dest.offset = xen_offset_in_page(mapping + off); + while (len-- != 0) if (mapping[off++] >= vif->num_queues) return XEN_NETIF_CTRL_STATUS_INVALID_PARAMETER; -- 2.34.1