Messages in this thread | | | Date | Tue, 25 Jul 2023 15:30:07 +0800 | From | Hangbin Liu <> | Subject | Re: [PATCH v2] rtnetlink: let rtnl_bridge_setlink checks IFLA_BRIDGE_MODE length |
| |
Hi Ma Lin,
Please add the target branch in your subject. e.g. [PATCHv2 net]
On Tue, Jul 25, 2023 at 01:57:06PM +0800, Lin Ma wrote: > There are totally 9 ndo_bridge_setlink handlers in the current kernel, > which are 1) bnxt_bridge_setlink, 2) be_ndo_bridge_setlink 3) > i40e_ndo_bridge_setlink 4) ice_bridge_setlink 5) > ixgbe_ndo_bridge_setlink 6) mlx5e_bridge_setlink 7) > nfp_net_bridge_setlink 8) qeth_l2_bridge_setlink 9) br_setlink. > > By investigating the code, we find that 1-7 parse and use nlattr > IFLA_BRIDGE_MODE but 3 and 4 forget to do the nla_len check. This can > lead to an out-of-attribute read and allow a malformed nlattr (e.g., > length 0) to be viewed as a 2 byte integer. > > To avoid such issues, also for other ndo_bridge_setlink handlers in the > future. This patch adds the nla_len check in rtnl_bridge_setlink and > does an early error return if length mismatches. To make it works, the > break is removed from the parsing for IFLA_BRIDGE_FLAGS to make sure > this nla_for_each_nested iterates every attribute.
Since you have checked the length in rtnl_bridge_setlink(). Can we remove the check in the driver handlers to avoid duplicate code? You can hold on this update and see if others have different opinion.
Thanks Hangbin
> > Fixes: b1edc14a3fbf ("ice: Implement ice_bridge_getlink and ice_bridge_setlink") > Fixes: 51616018dd1b ("i40e: Add support for getlink, setlink ndo ops") > Suggested-by: Jakub Kicinski <kuba@kernel.org> > Signed-off-by: Lin Ma <linma@zju.edu.cn> > --- > V1 -> V2: removes the break in parsing for IFLA_BRIDGE_FLAGS suggested > by Hangbin Liu <liuhangbin@gmail.com> > > net/core/rtnetlink.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c > index 3ad4e030846d..aef25aa5cf1d 100644 > --- a/net/core/rtnetlink.c > +++ b/net/core/rtnetlink.c > @@ -5140,13 +5140,17 @@ static int rtnl_bridge_setlink(struct sk_buff *skb, struct nlmsghdr *nlh, > br_spec = nlmsg_find_attr(nlh, sizeof(struct ifinfomsg), IFLA_AF_SPEC); > if (br_spec) { > nla_for_each_nested(attr, br_spec, rem) { > - if (nla_type(attr) == IFLA_BRIDGE_FLAGS) { > + if (nla_type(attr) == IFLA_BRIDGE_FLAGS && !have_flags) { > if (nla_len(attr) < sizeof(flags)) > return -EINVAL; > > have_flags = true; > flags = nla_get_u16(attr); > - break; > + } > + > + if (nla_type(attr) == IFLA_BRIDGE_MODE) { > + if (nla_len(attr) < sizeof(u16)) > + return -EINVAL; > } > } > } > -- > 2.17.1 >
| |