Re: [Xen-devel] [PATCH] stubdom: fix lwip compile

[Samuel Thibault <samuel.thibault@xxxxxxxxxxxx>]

Olaf Hering, le Wed 17 Sep 2014 11:41:09 +0200, a écrit :
> stubdom/lwip-x86_64/src/core/dhcp.c: In function 'dhcp_create_request':
> stubdom/lwip-x86_64/src/core/dhcp.c:1359:71: error: array subscript is above 
> array bounds [-Werror=array-bounds]
>      dhcp->msg_out->chaddr[i] = (i < netif->hwaddr_len) ? netif->hwaddr[i] : 
> 0/* pad byte*/;
> 
> gcc-4.8 can not know if hwaddr_len exceeds the hwaddr array size,
> so force an upper limit to assist gcc.
> 
> Signed-off-by: Olaf Hering <olaf@xxxxxxxxx>

That seems like the most reasonable and efficient solution indeed.

Acked-by: Samuel Thibault <samuel.thibault@xxxxxxxxxxxx>

> ---
>  stubdom/Makefile                                  |  1 +
>  stubdom/lwip.dhcp_create_request-hwaddr_len.patch | 26 
> +++++++++++++++++++++++
>  2 files changed, 27 insertions(+)
>  create mode 100644 stubdom/lwip.dhcp_create_request-hwaddr_len.patch
> 
> diff --git a/stubdom/Makefile b/stubdom/Makefile
> index 6bea68b..88da991 100644
> --- a/stubdom/Makefile
> +++ b/stubdom/Makefile
> @@ -145,6 +145,7 @@ lwip-$(XEN_TARGET_ARCH): lwip-$(LWIP_VERSION).tar.gz
>       tar xzf $<
>       mv lwip $@
>       patch -d $@ -p0 < lwip.patch-cvs
> +     patch -d $@ -p0 < lwip.dhcp_create_request-hwaddr_len.patch
>       touch $@
>  
>  #############
> diff --git a/stubdom/lwip.dhcp_create_request-hwaddr_len.patch 
> b/stubdom/lwip.dhcp_create_request-hwaddr_len.patch
> new file mode 100644
> index 0000000..12f1014
> --- /dev/null
> +++ b/stubdom/lwip.dhcp_create_request-hwaddr_len.patch
> @@ -0,0 +1,26 @@
> +---
> + lwip-x86_64/src/core/dhcp.c |    4 +++-
> + 1 file changed, 3 insertions(+), 1 deletion(-)
> +
> +Index: src/core/dhcp.c
> +===================================================================
> +--- src/core/dhcp.c
> ++++ src/core/dhcp.c
> +@@ -1322,6 +1322,8 @@ dhcp_create_request(struct netif *netif)
> + {
> +   struct dhcp *dhcp;
> +   u16_t i;
> ++  /* gcc can not know if hwaddr_len exceeds the hwaddr array size */
> ++  u8_t hwaddr_len = netif->hwaddr_len > NETIF_MAX_HWADDR_LEN ? 
> NETIF_MAX_HWADDR_LEN : netif->hwaddr_len;
> +   LWIP_ERROR("dhcp_create_request: netif != NULL", (netif != NULL), return 
> ERR_ARG;);
> +   dhcp = netif->dhcp;
> +   LWIP_ERROR("dhcp_create_request: dhcp != NULL", (dhcp != NULL), return 
> ERR_VAL;);
> +@@ -1356,7 +1358,7 @@ dhcp_create_request(struct netif *netif)
> +   dhcp->msg_out->giaddr.addr = 0;
> +   for (i = 0; i < DHCP_CHADDR_LEN; i++) {
> +     /* copy netif hardware address, pad with zeroes */
> +-    dhcp->msg_out->chaddr[i] = (i < netif->hwaddr_len) ? netif->hwaddr[i] : 
> 0/* pad byte*/;
> ++    dhcp->msg_out->chaddr[i] = (i < hwaddr_len) ? netif->hwaddr[i] : 0/* 
> pad byte*/;
> +   }
> +   for (i = 0; i < DHCP_SNAME_LEN; i++) {
> +     dhcp->msg_out->sname[i] = 0;
> 

-- 
Samuel
"I once witnessed a long-winded, month-long flamewar over the use of
mice vs. trackballs...It was very silly."
(By Matt Welsh)

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