On Fri, 2017-03-24 at 18:06 -0700, Matthias Kaehlcke wrote:
> __ieee80211_amsdu_copy_frag intentionally initializes a pointer to
> array[-1] to increment it later to valid values. clang rightfully
> generates an array-bounds warning on the initialization statement.
> Work around this by initializing the pointer to array[0] and
> decrementing it later, which allows to leave the rest of the
> algorithm untouched.
>
> Signed-off-by: Matthias Kaehlcke <m...@chromium.org>
> ---
> net/wireless/util.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/net/wireless/util.c b/net/wireless/util.c
> index 68e5f2ecee1a..d3d459e4a070 100644
> --- a/net/wireless/util.c
> +++ b/net/wireless/util.c
> @@ -659,7 +659,7 @@ __ieee80211_amsdu_copy_frag(struct sk_buff *skb,
> struct sk_buff *frame,
> int offset, int len)
> {
> struct skb_shared_info *sh = skb_shinfo(skb);
> - const skb_frag_t *frag = &sh->frags[-1];
> + const skb_frag_t *frag = &sh->frags[0];
> struct page *frag_page;
> void *frag_ptr;
> int frag_len, frag_size;
> @@ -669,6 +669,7 @@ __ieee80211_amsdu_copy_frag(struct sk_buff *skb,
> struct sk_buff *frame,
> frag_page = virt_to_head_page(skb->head);
> frag_ptr = skb->data;
> frag_size = head_size;
> + frag--;
Isn't it just a question of time until the compiler will see through
this trick and warn about it?
johannes
