On 22 December 2016 at 08:49, Maxim Uvarov <maxim.uva...@linaro.org> wrote:
> On debian jessie gcc unable to compile current code
> with error:
> odp_packet.c: In function 'odp_packet_trunc_head':
> odp_packet.c:314:46: error: array subscript is above array bounds
> [-Werror=array-bounds]
> to->buf_hdr.seg[i].len = from->buf_hdr.seg[num + i].len;
>
> The problem is that it breaks compilation only on .len line:
> for (i = 0; i < num; i++) {
> to->buf_hdr.seg[i].hdr = from->buf_hdr.seg[num + i].hdr;
> to->buf_hdr.seg[i].data = from->buf_hdr.seg[num + i].data;
> to->buf_hdr.seg[i].len = from->buf_hdr.seg[num + i].len;
> }
>
> If that line is commented out compilation passes. If lines are reordered
> than compilation also fails on .len line. Because there is no warning on
> .hdr and .data it looks like compiler error. Additional check for
> preconfigured value is workaround to that situation.
>
> Signed-off-by: Maxim Uvarov <maxim.uva...@linaro.org>
>
Reviewed-by: Mike Holmes <mike.hol...@linaro.org>
-O3 now passes for me on x86 gcc (Ubuntu 6.2.0-5ubuntu12) 6.2.0 20161005
> ---
> v2: - add comment (Mike)
> - in description .len line reorder does not fix compilation (Bill)
>
> platform/linux-generic/odp_packet.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/platform/linux-generic/odp_packet.c
> b/platform/linux-generic/odp_packet.c
> index 0d3fd05..599d839 100644
> --- a/platform/linux-generic/odp_packet.c
> +++ b/platform/linux-generic/odp_packet.c
> @@ -309,6 +309,10 @@ static inline void copy_num_segs(odp_packet_hdr_t
> *to, odp_packet_hdr_t *from,
> int i;
>
> for (i = 0; i < num; i++) {
> + /* check bellow also fixes gcc bug, refer to corresponding
> + * git commit */
> + if (odp_unlikely((num + i) >= CONFIG_PACKET_MAX_SEGS))
> + ODP_ABORT("packet segmenation error\n");
> to->buf_hdr.seg[i].hdr = from->buf_hdr.seg[num + i].hdr;
> to->buf_hdr.seg[i].data = from->buf_hdr.seg[num + i].data;
> to->buf_hdr.seg[i].len = from->buf_hdr.seg[num + i].len;
> --
> 2.7.1.250.gff4ea60
>
>
--
Mike Holmes
Program Manager - Linaro Networking Group
Linaro.org <http://www.linaro.org/> *│ *Open source software for ARM SoCs
"Work should be fun and collaborative, the rest follows"
