4.9-stable review patch. If anyone has any objections, please let me know.
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From: Jan Beulich JBeulich@suse.com
commit 780e83c259fc33e8959fed8dfdad17e378d72b62 upstream.
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 fwilhelm@google.com Signed-off-by: Jan Beulich jbeulich@suse.com Reviewed-by: Paul Durrant paul.durrant@citrix.com Tested-by: Paul Durrant paul.durrant@citrix.com Cc: stable@vger.kernel.org [4.7 onwards] Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/net/xen-netback/hash.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-)
--- 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 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;