On Fri, Jun 12, 2015 at 7:31 PM, Eric Dumazet <eric.duma...@gmail.com> wrote:
> From: Eric Dumazet <eduma...@google.com>
>
> __skb_header_pointer() returns a pointer that must be checked.
>
> Fixes infinite loop reported by Alexei, and add __must_check to
> catch these errors earlier.
>
> Fixes: 6a74fcf426f5 ("flow_dissector: add support for dst, hop-by-hop and
> routing ext hdrs")
> Reported-by: Alexei Starovoitov <alexei.starovoi...@gmail.com>
> Tested-by: Alexei Starovoitov <alexei.starovoi...@gmail.com>
> Signed-off-by: Eric Dumazet <eduma...@google.com>
> ---
> include/linux/skbuff.h | 9 +++++----
> net/core/flow_dissector.c | 6 ++++--
> 2 files changed, 9 insertions(+), 6 deletions(-)
>
> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
> index
> cc612fc0a8943ec853b92e6b3516b0e5582299e2..a7acc92aa6685d7006077510697e3d9481b02588
> 100644
> --- a/include/linux/skbuff.h
> +++ b/include/linux/skbuff.h
> @@ -2743,8 +2743,9 @@ __wsum __skb_checksum(const struct sk_buff *skb, int
> offset, int len,
> __wsum skb_checksum(const struct sk_buff *skb, int offset, int len,
> __wsum csum);
>
> -static inline void *__skb_header_pointer(const struct sk_buff *skb, int
> offset,
> - int len, void *data, int hlen, void
> *buffer)
> +static inline void * __must_check
> +__skb_header_pointer(const struct sk_buff *skb, int offset,
> + int len, void *data, int hlen, void *buffer)
> {
> if (hlen - offset >= len)
> return data + offset;
> @@ -2756,8 +2757,8 @@ static inline void *__skb_header_pointer(const struct
> sk_buff *skb, int offset,
> return buffer;
> }
>
> -static inline void *skb_header_pointer(const struct sk_buff *skb, int offset,
> - int len, void *buffer)
> +static inline void * __must_check
> +skb_header_pointer(const struct sk_buff *skb, int offset, int len, void
> *buffer)
> {
> return __skb_header_pointer(skb, offset, len, skb->data,
> skb_headlen(skb), buffer);
> diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
> index
> 22e4dffa0c8b3b9a20a7324eae1627313e14ce30..476e5dda59e19822dba98a931369ff2666c59c0d
> 100644
> --- a/net/core/flow_dissector.c
> +++ b/net/core/flow_dissector.c
> @@ -394,9 +394,11 @@ ip_proto_again:
>
> opthdr = __skb_header_pointer(skb, nhoff, sizeof(_opthdr),
> data, hlen, &_opthdr);
> + if (!opthdr)
> + return false;
>
> - ip_proto = _opthdr[0];
> - nhoff += (_opthdr[1] + 1) << 3;
> + ip_proto = opthdr[0];
> + nhoff += (opthdr[1] + 1) << 3;
>
> goto ip_proto_again;
> }
>
>
Acked-by: Tom Herbert <t...@herbertland.com>
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