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netfilter: x_tables: fix possible ZERO_SIZE_PTR pointer dereferencing error.

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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>
This commit is contained in:
Xiubo Li
2016-06-02 10:59:56 +08:00
committed by Pablo Neira Ayuso
parent 436a850dd9
commit a6d0bae148
1 changed files with 3 additions and 0 deletions
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3
net/netfilter/x_tables.c
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@@ -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);