Commit a6d0bae1 authored Jun 02, 2016 by Xiubo Li Committed by Pablo Neira Ayuso Jun 23, 2016

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 <lixiubo@cmss.chinamobile.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

parent 436a850d

net/netfilter/x_tables.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -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);

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