[PATCH] xfrm: use ISO C standard for array in linux/xfrm.h

From: Nicolas Dichtel <redacted>

Use the ISO C standard compliant form instead of the gcc extension.

Signed-off-by: Nicolas Dichtel <redacted>
---
 include/uapi/linux/xfrm.h | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/include/uapi/linux/xfrm.h b/include/uapi/linux/xfrm.h
index 28e493b..6a6a605 100644
--- a/include/uapi/linux/xfrm.h
+++ b/include/uapi/linux/xfrm.h

@@ -30,7 +30,7 @@ struct xfrm_sec_ctx {
 	__u8	ctx_alg;
 	__u16	ctx_len;
 	__u32	ctx_sid;
-	char	ctx_str[0];
+	char	ctx_str[];
 };
 
 /* Security Context Domains of Interpretation */

@@ -93,27 +93,27 @@ struct xfrm_replay_state_esn {
 	__u32		oseq_hi;
 	__u32		seq_hi;
 	__u32		replay_window;
-	__u32		bmp[0];
+	__u32		bmp[];
 };
 
 struct xfrm_algo {
 	char		alg_name[64];
 	unsigned int	alg_key_len;    /* in bits */
-	char		alg_key[0];
+	char		alg_key[];
 };
 
 struct xfrm_algo_auth {
 	char		alg_name[64];
 	unsigned int	alg_key_len;    /* in bits */
 	unsigned int	alg_trunc_len;  /* in bits */
-	char		alg_key[0];
+	char		alg_key[];
 };
 
 struct xfrm_algo_aead {
 	char		alg_name[64];
 	unsigned int	alg_key_len;	/* in bits */
 	unsigned int	alg_icv_len;	/* in bits */
-	char		alg_key[0];
+	char		alg_key[];
 };
 
 struct xfrm_stats {

-- 
1.7.12

On Tue, Oct 16, 2012 at 05:42:33PM +0200, nicolas.dichtel@6wind.com wrote:

Hm, what's the benefit of such a change? The kernel source is full
of these foo[0] type arrays. I don't see a reason to change this
just for xfrm.

From: Steffen Klassert <steffen.klassert@secunet.com>
Date: Wed, 17 Oct 2012 07:43:43 +0200

On Tue, Oct 16, 2012 at 05:42:33PM +0200, nicolas.dichtel@6wind.com wrote:

quoted

From: Nicolas Dichtel <redacted>

Use the ISO C standard compliant form instead of the gcc extension.

Signed-off-by: Nicolas Dichtel <redacted>
---
 include/uapi/linux/xfrm.h | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/include/uapi/linux/xfrm.h b/include/uapi/linux/xfrm.h
index 28e493b..6a6a605 100644
--- a/include/uapi/linux/xfrm.h
+++ b/include/uapi/linux/xfrm.h

@@ -30,7 +30,7 @@ struct xfrm_sec_ctx {
 	__u8	ctx_alg;
 	__u16	ctx_len;
 	__u32	ctx_sid;
-	char	ctx_str[0];
+	char	ctx_str[];

Hm, what's the benefit of such a change? The kernel source is full
of these foo[0] type arrays. I don't see a reason to change this
just for xfrm.

Agreed.

Le 17/10/2012 07:43, Steffen Klassert a écrit :

On Tue, Oct 16, 2012 at 05:42:33PM +0200, nicolas.dichtel@6wind.com wrote:

quoted

From: Nicolas Dichtel <redacted>

Use the ISO C standard compliant form instead of the gcc extension.

Signed-off-by: Nicolas Dichtel <redacted>
---
  include/uapi/linux/xfrm.h | 10 +++++-----
  1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/include/uapi/linux/xfrm.h b/include/uapi/linux/xfrm.h
index 28e493b..6a6a605 100644
--- a/include/uapi/linux/xfrm.h
+++ b/include/uapi/linux/xfrm.h

@@ -30,7 +30,7 @@ struct xfrm_sec_ctx {
  	__u8	ctx_alg;
  	__u16	ctx_len;
  	__u32	ctx_sid;
-	char	ctx_str[0];
+	char	ctx_str[];

Hm, what's the benefit of such a change? The kernel source is full
of these foo[0] type arrays. I don't see a reason to change this
just for xfrm.

We got a problem with "ip xfrm state add" when compiled with gcc 4.4.6.
Error was "*** buffer overflow detected ***: ip terminated", because when we try to copy the key in struct xfrm_algo, the function strncpy() calls some builtin checks about the size of the destination buffer, which is 0. With the standard notation, there is no problem.

With gcc 4.7.0, there is no problem, I don't know exactly which version of gcc triggers the problem.

On Wed, Oct 17, 2012 at 09:50:58AM +0200, Nicolas Dichtel wrote:

We got a problem with "ip xfrm state add" when compiled with gcc 4.4.6.
Error was "*** buffer overflow detected ***: ip terminated", because
when we try to copy the key in struct xfrm_algo, the function
strncpy() calls some builtin checks about the size of the
destination buffer, which is 0. With the standard notation, there is
no problem.

This is likely to be a gcc FORITFY bug. Try to build iproute2 with
the -D_FORTIFY_SOURCE=0 flag.

Le 17/10/2012 10:27, Steffen Klassert a écrit :

On Wed, Oct 17, 2012 at 09:50:58AM +0200, Nicolas Dichtel wrote:

quoted

We got a problem with "ip xfrm state add" when compiled with gcc 4.4.6.
Error was "*** buffer overflow detected ***: ip terminated", because
when we try to copy the key in struct xfrm_algo, the function
strncpy() calls some builtin checks about the size of the
destination buffer, which is 0. With the standard notation, there is
no problem.

This is likely to be a gcc FORITFY bug. Try to build iproute2 with
the -D_FORTIFY_SOURCE=0 flag.

Right, it works. Thank you.