Kees Cook <keescook@xxxxxxxxxxxx> wrote: > In the quest to remove all stack VLA usage from the kernel[1], this > allocates the maximum size expected for all possible attrs and adds > a sanity-check to make sure nothing gets out of sync. > > [1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@xxxxxxxxxxxxxx > > Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> > --- > net/netfilter/nfnetlink.c | 22 ++++++++++++++++++++-- > 1 file changed, 20 insertions(+), 2 deletions(-) > > diff --git a/net/netfilter/nfnetlink.c b/net/netfilter/nfnetlink.c > index 03ead8a9e90c..0cb395f9627e 100644 > --- a/net/netfilter/nfnetlink.c > +++ b/net/netfilter/nfnetlink.c > @@ -28,6 +28,7 @@ > > #include <net/netlink.h> > #include <linux/netfilter/nfnetlink.h> > +#include <linux/netfilter/nf_tables.h> > > const struct nfnetlink_subsystem __rcu *subsys; > @@ -185,11 +191,17 @@ static int nfnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh, > { > int min_len = nlmsg_total_size(sizeof(struct nfgenmsg)); > u8 cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type); > - struct nlattr *cda[ss->cb[cb_id].attr_count + 1]; > + struct nlattr *cda[NFTA_MAX_ATTR + 1]; > struct nlattr *attr = (void *)nlh + min_len; > int attrlen = nlh->nlmsg_len - min_len; > __u8 subsys_id = NFNL_SUBSYS_ID(type); > > + /* Sanity-check NFTA_MAX_ATTR */ > + if (ss->cb[cb_id].attr_count > NFTA_MAX_ATTR) { > + rcu_read_unlock(); > + return -ENOMEM; > + } Would you mind also adding check to nfnetlink_subsys_register, plus WARN()? That way we'll see that NFTA_MAX_ATTR isn't large enough by virtue of registration rather than actual use. Other than that this looks fine to me. -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
