Re: [PATCH v2] bpf: Add length check for SK_DIAG_BPF_STORAGE_REQ_MAP_FD parsing

[Jakub Kicinski]

On Tue, 25 Jul 2023 10:33:30 +0800 Lin Ma wrote:
> The nla_for_each_nested parsing in function bpf_sk_storage_diag_alloc
> does not check the length of the nested attribute. This can lead to an
> out-of-attribute read and allow a malformed nlattr (e.g., length 0) to
> be viewed as a 4 byte integer.
> 
> This patch adds an additional check when the nlattr is getting counted.
> This makes sure the latter nla_get_u32 can access the attributes with
> the correct length.
> 
> Fixes: 1ed4d92458a9 ("bpf: INET_DIAG support in bpf_sk_storage")
> Suggested-by: Jakub Kicinski <kuba@xxxxxxxxxx>
> Signed-off-by: Lin Ma <linma@xxxxxxxxxx>

Reviewed-by: Jakub Kicinski <kuba@xxxxxxxxxx>

Those who parse manually must do checks manually. It is what it is.