In preparation to enabling -Wvla, remove VLA and replace it with dynamic memory allocation.
>From a security viewpoint, the use of Variable Length Arrays can be a vector for stack overflow attacks. Also, in general, as the code evolves it is easy to lose track of how big a VLA can get. Thus, we can end up having segfaults that are hard to debug. Also, fixed as part of the directive to remove all VLAs from the kernel: https://lkml.org/lkml/2018/3/7/621 Signed-off-by: Gustavo A. R. Silva <gust...@embeddedor.com> --- net/netfilter/nfnetlink_cttimeout.c | 26 +++++++++++++++++--------- 1 file changed, 17 insertions(+), 9 deletions(-) diff --git a/net/netfilter/nfnetlink_cttimeout.c b/net/netfilter/nfnetlink_cttimeout.c index 6819300..dcd7bd3 100644 --- a/net/netfilter/nfnetlink_cttimeout.c +++ b/net/netfilter/nfnetlink_cttimeout.c @@ -51,19 +51,27 @@ ctnl_timeout_parse_policy(void *timeouts, const struct nf_conntrack_l4proto *l4proto, struct net *net, const struct nlattr *attr) { + struct nlattr **tb; int ret = 0; - if (likely(l4proto->ctnl_timeout.nlattr_to_obj)) { - struct nlattr *tb[l4proto->ctnl_timeout.nlattr_max+1]; + if (!l4proto->ctnl_timeout.nlattr_to_obj) + return 0; - ret = nla_parse_nested(tb, l4proto->ctnl_timeout.nlattr_max, - attr, l4proto->ctnl_timeout.nla_policy, - NULL); - if (ret < 0) - return ret; + tb = kcalloc(l4proto->ctnl_timeout.nlattr_max + 1, sizeof(*tb), + GFP_KERNEL); - ret = l4proto->ctnl_timeout.nlattr_to_obj(tb, net, timeouts); - } + if (!tb) + return -ENOMEM; + + ret = nla_parse_nested(tb, l4proto->ctnl_timeout.nlattr_max, attr, + l4proto->ctnl_timeout.nla_policy, NULL); + if (ret < 0) + goto err; + + ret = l4proto->ctnl_timeout.nlattr_to_obj(tb, net, timeouts); + +err: + kfree(tb); return ret; } -- 2.7.4
