2023-01-05 23:00:42

by Kees Cook

[permalink] [raw]
Subject: [PATCH] net: ipv6: rpl_iptunnel: Replace 0-length arrays with flexible arrays

Zero-length arrays are deprecated[1]. Replace struct ipv6_rpl_sr_hdr's
"segments" union of 0-length arrays with flexible arrays. Detected with
GCC 13, using -fstrict-flex-arrays=3:

In function 'rpl_validate_srh',
inlined from 'rpl_build_state' at ../net/ipv6/rpl_iptunnel.c:96:7:
../net/ipv6/rpl_iptunnel.c:60:28: warning: array subscript <unknown> is outside array bounds of 'struct in6_addr[0]' [-Warray-bounds=]
60 | if (ipv6_addr_type(&srh->rpl_segaddr[srh->segments_left - 1]) &
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from ../include/net/rpl.h:12,
from ../net/ipv6/rpl_iptunnel.c:13:
../include/uapi/linux/rpl.h: In function 'rpl_build_state':
../include/uapi/linux/rpl.h:40:33: note: while referencing 'addr'
40 | struct in6_addr addr[0];
| ^~~~

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays

Cc: "David S. Miller" <[email protected]>
Cc: Hideaki YOSHIFUJI <[email protected]>
Cc: David Ahern <[email protected]>
Cc: Eric Dumazet <[email protected]>
Cc: Jakub Kicinski <[email protected]>
Cc: Paolo Abeni <[email protected]>
Cc: "Gustavo A. R. Silva" <[email protected]>
Cc: [email protected]
Signed-off-by: Kees Cook <[email protected]>
---
include/uapi/linux/rpl.h | 4 ++--
net/ipv6/rpl_iptunnel.c | 2 +-
2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/include/uapi/linux/rpl.h b/include/uapi/linux/rpl.h
index 708adddf9f13..7c8970e5b84b 100644
--- a/include/uapi/linux/rpl.h
+++ b/include/uapi/linux/rpl.h
@@ -37,8 +37,8 @@ struct ipv6_rpl_sr_hdr {
#endif

union {
- struct in6_addr addr[0];
- __u8 data[0];
+ __DECLARE_FLEX_ARRAY(struct in6_addr, addr);
+ __DECLARE_FLEX_ARRAY(__u8, data);
} segments;
} __attribute__((packed));

diff --git a/net/ipv6/rpl_iptunnel.c b/net/ipv6/rpl_iptunnel.c
index ff691d9f4a04..b1c028df686e 100644
--- a/net/ipv6/rpl_iptunnel.c
+++ b/net/ipv6/rpl_iptunnel.c
@@ -13,7 +13,7 @@
#include <net/rpl.h>

struct rpl_iptunnel_encap {
- struct ipv6_rpl_sr_hdr srh[0];
+ DECLARE_FLEX_ARRAY(struct ipv6_rpl_sr_hdr, srh);
};

struct rpl_lwt {
--
2.34.1


2023-01-06 16:17:58

by Gustavo A. R. Silva

[permalink] [raw]
Subject: Re: [PATCH] net: ipv6: rpl_iptunnel: Replace 0-length arrays with flexible arrays

On Thu, Jan 05, 2023 at 02:15:37PM -0800, Kees Cook wrote:
> Zero-length arrays are deprecated[1]. Replace struct ipv6_rpl_sr_hdr's
> "segments" union of 0-length arrays with flexible arrays. Detected with
> GCC 13, using -fstrict-flex-arrays=3:
>
> In function 'rpl_validate_srh',
> inlined from 'rpl_build_state' at ../net/ipv6/rpl_iptunnel.c:96:7:
> ../net/ipv6/rpl_iptunnel.c:60:28: warning: array subscript <unknown> is outside array bounds of 'struct in6_addr[0]' [-Warray-bounds=]
> 60 | if (ipv6_addr_type(&srh->rpl_segaddr[srh->segments_left - 1]) &
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> In file included from ../include/net/rpl.h:12,
> from ../net/ipv6/rpl_iptunnel.c:13:
> ../include/uapi/linux/rpl.h: In function 'rpl_build_state':
> ../include/uapi/linux/rpl.h:40:33: note: while referencing 'addr'
> 40 | struct in6_addr addr[0];
> | ^~~~
>
> [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays
>
> Cc: "David S. Miller" <[email protected]>
> Cc: Hideaki YOSHIFUJI <[email protected]>
> Cc: David Ahern <[email protected]>
> Cc: Eric Dumazet <[email protected]>
> Cc: Jakub Kicinski <[email protected]>
> Cc: Paolo Abeni <[email protected]>
> Cc: "Gustavo A. R. Silva" <[email protected]>
> Cc: [email protected]
> Signed-off-by: Kees Cook <[email protected]>

Reviewed-by: Gustavo A. R. Silva <[email protected]>

Thanks!
--
Gustavo

> ---
> include/uapi/linux/rpl.h | 4 ++--
> net/ipv6/rpl_iptunnel.c | 2 +-
> 2 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/include/uapi/linux/rpl.h b/include/uapi/linux/rpl.h
> index 708adddf9f13..7c8970e5b84b 100644
> --- a/include/uapi/linux/rpl.h
> +++ b/include/uapi/linux/rpl.h
> @@ -37,8 +37,8 @@ struct ipv6_rpl_sr_hdr {
> #endif
>
> union {
> - struct in6_addr addr[0];
> - __u8 data[0];
> + __DECLARE_FLEX_ARRAY(struct in6_addr, addr);
> + __DECLARE_FLEX_ARRAY(__u8, data);
> } segments;
> } __attribute__((packed));
>
> diff --git a/net/ipv6/rpl_iptunnel.c b/net/ipv6/rpl_iptunnel.c
> index ff691d9f4a04..b1c028df686e 100644
> --- a/net/ipv6/rpl_iptunnel.c
> +++ b/net/ipv6/rpl_iptunnel.c
> @@ -13,7 +13,7 @@
> #include <net/rpl.h>
>
> struct rpl_iptunnel_encap {
> - struct ipv6_rpl_sr_hdr srh[0];
> + DECLARE_FLEX_ARRAY(struct ipv6_rpl_sr_hdr, srh);
> };
>
> struct rpl_lwt {
> --
> 2.34.1
>

2023-01-06 16:42:01

by David Ahern

[permalink] [raw]
Subject: Re: [PATCH] net: ipv6: rpl_iptunnel: Replace 0-length arrays with flexible arrays

On 1/5/23 3:15 PM, Kees Cook wrote:
> Zero-length arrays are deprecated[1]. Replace struct ipv6_rpl_sr_hdr's
> "segments" union of 0-length arrays with flexible arrays. Detected with
> GCC 13, using -fstrict-flex-arrays=3:
>
> In function 'rpl_validate_srh',
> inlined from 'rpl_build_state' at ../net/ipv6/rpl_iptunnel.c:96:7:
> ../net/ipv6/rpl_iptunnel.c:60:28: warning: array subscript <unknown> is outside array bounds of 'struct in6_addr[0]' [-Warray-bounds=]
> 60 | if (ipv6_addr_type(&srh->rpl_segaddr[srh->segments_left - 1]) &
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> In file included from ../include/net/rpl.h:12,
> from ../net/ipv6/rpl_iptunnel.c:13:
> ../include/uapi/linux/rpl.h: In function 'rpl_build_state':
> ../include/uapi/linux/rpl.h:40:33: note: while referencing 'addr'
> 40 | struct in6_addr addr[0];
> | ^~~~
>
> [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays
>
> Cc: "David S. Miller" <[email protected]>
> Cc: Hideaki YOSHIFUJI <[email protected]>
> Cc: David Ahern <[email protected]>
> Cc: Eric Dumazet <[email protected]>
> Cc: Jakub Kicinski <[email protected]>
> Cc: Paolo Abeni <[email protected]>
> Cc: "Gustavo A. R. Silva" <[email protected]>
> Cc: [email protected]
> Signed-off-by: Kees Cook <[email protected]>
> ---
> include/uapi/linux/rpl.h | 4 ++--
> net/ipv6/rpl_iptunnel.c | 2 +-
> 2 files changed, 3 insertions(+), 3 deletions(-)
>

Reviewed-by: David Ahern <[email protected]>

2023-01-07 03:48:03

by patchwork-bot+netdevbpf

[permalink] [raw]
Subject: Re: [PATCH] net: ipv6: rpl_iptunnel: Replace 0-length arrays with flexible arrays

Hello:

This patch was applied to netdev/net-next.git (master)
by Jakub Kicinski <[email protected]>:

On Thu, 5 Jan 2023 14:15:37 -0800 you wrote:
> Zero-length arrays are deprecated[1]. Replace struct ipv6_rpl_sr_hdr's
> "segments" union of 0-length arrays with flexible arrays. Detected with
> GCC 13, using -fstrict-flex-arrays=3:
>
> In function 'rpl_validate_srh',
> inlined from 'rpl_build_state' at ../net/ipv6/rpl_iptunnel.c:96:7:
> ../net/ipv6/rpl_iptunnel.c:60:28: warning: array subscript <unknown> is outside array bounds of 'struct in6_addr[0]' [-Warray-bounds=]
> 60 | if (ipv6_addr_type(&srh->rpl_segaddr[srh->segments_left - 1]) &
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> In file included from ../include/net/rpl.h:12,
> from ../net/ipv6/rpl_iptunnel.c:13:
> ../include/uapi/linux/rpl.h: In function 'rpl_build_state':
> ../include/uapi/linux/rpl.h:40:33: note: while referencing 'addr'
> 40 | struct in6_addr addr[0];
> | ^~~~
>
> [...]

Here is the summary with links:
- net: ipv6: rpl_iptunnel: Replace 0-length arrays with flexible arrays
https://git.kernel.org/netdev/net-next/c/e8d283b6cf0e

You are awesome, thank you!
--
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html