From a6d0bae14858a43ab9d76d6332d7c3f2a618a6a2 Mon Sep 17 00:00:00 2001 From: Xiubo Li Date: Thu, 2 Jun 2016 10:59:56 +0800 Subject: [PATCH] netfilter: x_tables: fix possible ZERO_SIZE_PTR pointer dereferencing error. Since we cannot make sure that the 'hook_mask' will always be none zero here. If it equals to zero, the num_hooks will be zero too, and then kmalloc() will return ZERO_SIZE_PTR, which is (void *)16. Then the following error check will fails: ops = kmalloc(sizeof(*ops) * num_hooks, GFP_KERNEL); if (ops == NULL) return ERR_PTR(-ENOMEM); So this patch will fix this with just doing the zero check before kmalloc() is called. Maybe the case above will never happen here, but in theory. Signed-off-by: Xiubo Li Signed-off-by: Pablo Neira Ayuso --- net/netfilter/x_tables.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c index c69c892231d7..8aff34e8737c 100644 --- a/net/netfilter/x_tables.c +++ b/net/netfilter/x_tables.c @@ -1460,6 +1460,9 @@ xt_hook_ops_alloc(const struct xt_table *table, nf_hookfn *fn) uint8_t hooknum; struct nf_hook_ops *ops; + if (!num_hooks) + return ERR_PTR(-EINVAL); + ops = kmalloc(sizeof(*ops) * num_hooks, GFP_KERNEL); if (ops == NULL) return ERR_PTR(-ENOMEM);