[PATCH net-next] ip_tunnel: harden copying IP tunnel params to userspace

[PATCH net-next] ip_tunnel: harden copying IP tunnel params to userspace

[Alexander Lobakin]

Structures which are about to be copied to userspace shouldn't have
uninitialized fields or paddings.
memset() the whole &ip_tunnel_parm in ip_tunnel_parm_to_user() before
filling it with the kernel data. The compilers will hopefully combine
writes to it.

Fixes: 117aef12a7b1 ("ip_tunnel: use a separate struct to store tunnel params in the kernel")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/netdev/5f63dd25-de94-4ca3-84e6-14095953db13@moroto.mountain
Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
---
 net/ipv4/ip_tunnel.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
index f63b573f66dc..6ec4365cefa5 100644
--- a/net/ipv4/ip_tunnel.c
+++ b/net/ipv4/ip_tunnel.c
@@ -1034,6 +1034,8 @@ bool ip_tunnel_parm_to_user(void __user *data, struct ip_tunnel_parm_kern *kp)
 	    !ip_tunnel_flags_is_be16_compat(kp->o_flags))
 		return false;
 
+	memset(&p, 0, sizeof(p));
+
 	strscpy(p.name, kp->name);
 	p.link = kp->link;
 	p.i_flags = ip_tunnel_flags_to_be16(kp->i_flags);
-- 
2.44.0

Re: [PATCH net-next] ip_tunnel: harden copying IP tunnel params to userspace

[Simon Horman]

On Thu, Apr 04, 2024 at 06:03:02PM +0200, Alexander Lobakin wrote:
> Structures which are about to be copied to userspace shouldn't have
> uninitialized fields or paddings.
> memset() the whole &ip_tunnel_parm in ip_tunnel_parm_to_user() before
> filling it with the kernel data. The compilers will hopefully combine
> writes to it.
> 
> Fixes: 117aef12a7b1 ("ip_tunnel: use a separate struct to store tunnel params in the kernel")
> Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
> Closes: https://lore.kernel.org/netdev/5f63dd25-de94-4ca3-84e6-14095953db13@moroto.mountain
> Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>

Reviewed-by: Simon Horman <horms@kernel.org>

Re: [PATCH net-next] ip_tunnel: harden copying IP tunnel params to userspace

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net-next.git (main)
by David S. Miller <davem@davemloft.net>:

On Thu,  4 Apr 2024 18:03:02 +0200 you wrote:
> Structures which are about to be copied to userspace shouldn't have
> uninitialized fields or paddings.
> memset() the whole &ip_tunnel_parm in ip_tunnel_parm_to_user() before
> filling it with the kernel data. The compilers will hopefully combine
> writes to it.
> 
> Fixes: 117aef12a7b1 ("ip_tunnel: use a separate struct to store tunnel params in the kernel")
> Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
> Closes: https://lore.kernel.org/netdev/5f63dd25-de94-4ca3-84e6-14095953db13@moroto.mountain
> Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
> 
> [...]

Here is the summary with links:
  - [net-next] ip_tunnel: harden copying IP tunnel params to userspace
    https://git.kernel.org/netdev/net-next/c/5a66cda52d7d

You are awesome, thank you!
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