[PATCH nf] netfilter: x_tables: suppress kmemcheck warning

[PATCH nf] netfilter: x_tables: suppress kmemcheck warning

[Florian Westphal]

Markus Trippelsdorf reports:

WARNING: kmemcheck: Caught 64-bit read from uninitialized memory (ffff88001e605480)
4055601e0088ffff000000000000000090686d81ffffffff0000000000000000
 u u u u u u u u u u u u u u u u i i i i i i i i u u u u u u u u
 ^
|RIP: 0010:[<ffffffff8166e561>]  [<ffffffff8166e561>] nf_register_net_hook+0x51/0x160
[..]
 [<ffffffff8166e561>] nf_register_net_hook+0x51/0x160
 [<ffffffff8166eaaf>] nf_register_net_hooks+0x3f/0xa0
 [<ffffffff816d6715>] ipt_register_table+0xe5/0x110
[..]

This warning is harmless; we copy 'uninitialized' data from the hook ops
but it will not be used.
Long term the structures keeping run-time data should be disentangled
from those only containing config-time data (such as where in the list
to insert a hook), but thats -next material.

Reported-by: Markus Trippelsdorf <markus@trippelsdorf.de>
Suggested-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Florian Westphal <fw@strlen.de>
---
 net/netfilter/x_tables.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c
index e0aa7c1d0224..fc4977456c30 100644
--- a/net/netfilter/x_tables.c
+++ b/net/netfilter/x_tables.c
@@ -1513,7 +1513,7 @@ xt_hook_ops_alloc(const struct xt_table *table, nf_hookfn *fn)
 	if (!num_hooks)
 		return ERR_PTR(-EINVAL);
 
-	ops = kmalloc(sizeof(*ops) * num_hooks, GFP_KERNEL);
+	ops = kcalloc(num_hooks, sizeof(*ops), GFP_KERNEL);
 	if (ops == NULL)
 		return ERR_PTR(-ENOMEM);
 
-- 
2.7.3

Re: [PATCH nf] netfilter: x_tables: suppress kmemcheck warning

[Aaron Conole]

Florian Westphal <fw@strlen.de> writes:

> Markus Trippelsdorf reports:
>
> WARNING: kmemcheck: Caught 64-bit read from uninitialized memory (ffff88001e605480)
> 4055601e0088ffff000000000000000090686d81ffffffff0000000000000000
>  u u u u u u u u u u u u u u u u i i i i i i i i u u u u u u u u
>  ^
> |RIP: 0010:[<ffffffff8166e561>]  [<ffffffff8166e561>] nf_register_net_hook+0x51/0x160
> [..]
>  [<ffffffff8166e561>] nf_register_net_hook+0x51/0x160
>  [<ffffffff8166eaaf>] nf_register_net_hooks+0x3f/0xa0
>  [<ffffffff816d6715>] ipt_register_table+0xe5/0x110
> [..]
>
> This warning is harmless; we copy 'uninitialized' data from the hook ops
> but it will not be used.
> Long term the structures keeping run-time data should be disentangled
> from those only containing config-time data (such as where in the list
> to insert a hook), but thats -next material.
>
> Reported-by: Markus Trippelsdorf <markus@trippelsdorf.de>
> Suggested-by: Al Viro <viro@ZenIV.linux.org.uk>
> Signed-off-by: Florian Westphal <fw@strlen.de>
> ---
>  net/netfilter/x_tables.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>

ACK

Re: [PATCH nf] netfilter: x_tables: suppress kmemcheck warning

[Pablo Neira Ayuso]

On Mon, Oct 17, 2016 at 09:50:23PM +0200, Florian Westphal wrote:
> Markus Trippelsdorf reports:
> 
> WARNING: kmemcheck: Caught 64-bit read from uninitialized memory (ffff88001e605480)
> 4055601e0088ffff000000000000000090686d81ffffffff0000000000000000
>  u u u u u u u u u u u u u u u u i i i i i i i i u u u u u u u u
>  ^
> |RIP: 0010:[<ffffffff8166e561>]  [<ffffffff8166e561>] nf_register_net_hook+0x51/0x160
> [..]
>  [<ffffffff8166e561>] nf_register_net_hook+0x51/0x160
>  [<ffffffff8166eaaf>] nf_register_net_hooks+0x3f/0xa0
>  [<ffffffff816d6715>] ipt_register_table+0xe5/0x110
> [..]
> 
> This warning is harmless; we copy 'uninitialized' data from the hook ops
> but it will not be used.
> Long term the structures keeping run-time data should be disentangled
> from those only containing config-time data (such as where in the list
> to insert a hook), but thats -next material.

Applied, thanks.