From: "Gustavo A. R. Silva" <gustavo@xxxxxxxxxxxxxx> 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 <gustavo@xxxxxxxxxxxxxx> Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx> --- net/netfilter/nf_tables_api.c | 23 +++++++++++++++-------- 1 file changed, 15 insertions(+), 8 deletions(-) diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index 8cc7fc970f0c..92f5606b0dea 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -4357,16 +4357,20 @@ static struct nft_object *nft_obj_init(const struct nft_ctx *ctx, const struct nft_object_type *type, const struct nlattr *attr) { - struct nlattr *tb[type->maxattr + 1]; + struct nlattr **tb; const struct nft_object_ops *ops; struct nft_object *obj; - int err; + int err = -ENOMEM; + + tb = kmalloc_array(type->maxattr + 1, sizeof(*tb), GFP_KERNEL); + if (!tb) + goto err1; if (attr) { err = nla_parse_nested(tb, type->maxattr, attr, type->policy, NULL); if (err < 0) - goto err1; + goto err2; } else { memset(tb, 0, sizeof(tb[0]) * (type->maxattr + 1)); } @@ -4375,7 +4379,7 @@ static struct nft_object *nft_obj_init(const struct nft_ctx *ctx, ops = type->select_ops(ctx, (const struct nlattr * const *)tb); if (IS_ERR(ops)) { err = PTR_ERR(ops); - goto err1; + goto err2; } } else { ops = type->ops; @@ -4383,18 +4387,21 @@ static struct nft_object *nft_obj_init(const struct nft_ctx *ctx, err = -ENOMEM; obj = kzalloc(sizeof(*obj) + ops->size, GFP_KERNEL); - if (obj == NULL) - goto err1; + if (!obj) + goto err2; err = ops->init(ctx, (const struct nlattr * const *)tb, obj); if (err < 0) - goto err2; + goto err3; obj->ops = ops; + kfree(tb); return obj; -err2: +err3: kfree(obj); +err2: + kfree(tb); err1: return ERR_PTR(err); } -- 2.11.0 -- 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
