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ipv6: ioam: Replace 0-length array with flexible array

PATCH Applied Kees Cook 4 participants 4 messages Jan 5, 2023 – Jan 7, 2023

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Kees Cook

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#0 lore raw

PATCH 1/1 ipv6: ioam: Replace 0-length array with flexible array

Zero-length arrays are deprecated[1]. Replace struct ioam6_trace_hdr's "data" 0-length array with a flexible array. Detected with GCC 13, using -fstrict-flex-arrays=3:

net/ipv6/ioam6_iptunnel.c: In function 'ioam6_build_state':
net/ipv6/ioam6_iptunnel.c:194:37: warning: array subscript <unknown> is outside array bounds of '__u8[0]' {aka 'unsigned char[]'} [-Warray-bounds=]

  194 |                 tuninfo->traceh.data[trace->remlen * 4] = IPV6_TLV_PADN;
      |                 ~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~
In file included from include/linux/ioam6.h:11,
                 from net/ipv6/ioam6_iptunnel.c:13:
include/uapi/linux/ioam6.h:130:17: note: while referencing 'data'
  130 |         __u8    data[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 Jakub Kicinski <[email protected]>
Cc Justin Iurman <[email protected]>
Cc Eric Dumazet <[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/ioam6.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
include/uapi/linux/ioam6.h +1 -1
index ac4de376f0ce..8f72b24fefb3 100644
@@ -127,7 +127,7 @@ struct ioam6_trace_hdr {
 #endif
 
 #define IOAM6_TRACE_DATA_SIZE_MAX 244
-	__u8	data[0];
+	__u8	data[];
 } __attribute__((packed));
 
 #endif /* _UAPI_LINUX_IOAM6_H */
Signature · 1 line
2.34.1
Reviewed-by on v1 1/1
#1 lore raw
Quoted 16 lines · Kees Cook

Zero-length arrays are deprecated[1]. Replace struct ioam6_trace_hdr's "data" 0-length array with a flexible array. Detected with GCC 13, using -fstrict-flex-arrays=3:

net/ipv6/ioam6_iptunnel.c: In function 'ioam6_build_state':
net/ipv6/ioam6_iptunnel.c:194:37: warning: array subscript <unknown> is outside array bounds of '__u8[0]' {aka 'unsigned char[]'} [-Warray-bounds=]

  194 |                 tuninfo->traceh.data[trace->remlen * 4] = IPV6_TLV_PADN;
      |                 ~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~
In file included from include/linux/ioam6.h:11,
                 from net/ipv6/ioam6_iptunnel.c:13:
include/uapi/linux/ioam6.h:130:17: note: while referencing 'data'
  130 |         __u8    data[0];
      |                 ^~~~

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

Quoted 8 lines
Cc "David S. Miller" <[email protected]>
Cc Jakub Kicinski <[email protected]>
Cc Justin Iurman <[email protected]>
Cc Eric Dumazet <[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

Quoted 20 lines
---
 include/uapi/linux/ioam6.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
include/uapi/linux/ioam6.h +1 -1
index ac4de376f0ce..8f72b24fefb3 100644
@@ -127,7 +127,7 @@ struct ioam6_trace_hdr {
 #endif
 
 #define IOAM6_TRACE_DATA_SIZE_MAX 244
-	__u8	data[0];
+	__u8	data[];
 } __attribute__((packed));
 
 #endif /* _UAPI_LINUX_IOAM6_H */
Signature · 1 line
2.34.1
Reviewed-by Tested-by on v1 1/1
#2 lore raw
In reply to Kees Cook
Quoted 16 lines · Kees Cook

Zero-length arrays are deprecated[1]. Replace struct ioam6_trace_hdr's "data" 0-length array with a flexible array. Detected with GCC 13, using -fstrict-flex-arrays=3:

net/ipv6/ioam6_iptunnel.c: In function 'ioam6_build_state':
net/ipv6/ioam6_iptunnel.c:194:37: warning: array subscript <unknown> is outside array bounds of '__u8[0]' {aka 'unsigned char[]'} [-Warray-bounds=]

   194 |                 tuninfo->traceh.data[trace->remlen * 4] = IPV6_TLV_PADN;
       |                 ~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~
In file included from include/linux/ioam6.h:11,
                  from net/ipv6/ioam6_iptunnel.c:13:
include/uapi/linux/ioam6.h:130:17: note: while referencing 'data'
   130 |         __u8    data[0];
       |                 ^~~~

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

Quoted 8 lines
Cc "David S. Miller" <[email protected]>
Cc Jakub Kicinski <[email protected]>
Cc Justin Iurman <[email protected]>
Cc Eric Dumazet <[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 Justin Iurman <[email protected]>
Tested-by Justin Iurman <[email protected]>

LGTM, thanks.

Quoted 17 lines
---
  include/uapi/linux/ioam6.h | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)
include/uapi/linux/ioam6.h +1 -1
index ac4de376f0ce..8f72b24fefb3 100644
@@ -127,7 +127,7 @@ struct ioam6_trace_hdr {
  #endif
 
  #define IOAM6_TRACE_DATA_SIZE_MAX 244
-	__u8	data[0];
+	__u8	data[];
  } __attribute__((packed));
 
  #endif /* _UAPI_LINUX_IOAM6_H */
CI Applied
#3 lore raw
In reply to Kees Cook
This patch was applied to netdev/net-next.git (master) by Jakub Kicinski <[email protected]>:

Hello:

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

Quoted 14 lines · On Thu, 5 Jan 2023 14:21:16 -0800 you wrote:

Zero-length arrays are deprecated[1]. Replace struct ioam6_trace_hdr's "data" 0-length array with a flexible array. Detected with GCC 13, using -fstrict-flex-arrays=3:

net/ipv6/ioam6_iptunnel.c: In function 'ioam6_build_state':
net/ipv6/ioam6_iptunnel.c:194:37: warning: array subscript <unknown> is outside array bounds of '__u8[0]' {aka 'unsigned char[]'} [-Warray-bounds=]

  194 |                 tuninfo->traceh.data[trace->remlen * 4] = IPV6_TLV_PADN;
      |                 ~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~
In file included from include/linux/ioam6.h:11,
                 from net/ipv6/ioam6_iptunnel.c:13:
include/uapi/linux/ioam6.h:130:17: note: while referencing 'data'
  130 |         __u8    data[0];
      |                 ^~~~
Quoted 1 line

[...]

Here is the summary with links:
- ipv6: ioam: Replace 0-length array with flexible array

    https://git.kernel.org/netdev/net-next/c/0b5dfa35da03

You are awesome, thank you!

Signature · 2 lines
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