[PATCH][next] cifs: Replace zero-length arrays with flexible-array members

[PATCH][next] cifs: Replace zero-length arrays with flexible-array members

[Gustavo A. R. Silva]

Zero-length arrays are deprecated[1] and we are moving towards
adopting C99 flexible-array members instead. So, replace zero-length
arrays in a couple of structures with flex-array members.

This helps with the ongoing efforts to tighten the FORTIFY_SOURCE
routines on memcpy() and help us make progress towards globally
enabling -fstrict-flex-arrays=3 [2].

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays [1]
Link: https://gcc.gnu.org/pipermail/gcc-patches/2022-October/602902.html [2]
Link: https://github.com/KSPP/linux/issues/78
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
 fs/cifs/ntlmssp.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/cifs/ntlmssp.h b/fs/cifs/ntlmssp.h
index 55758b9ec877..2c5dde2ece58 100644
--- a/fs/cifs/ntlmssp.h
+++ b/fs/cifs/ntlmssp.h
@@ -83,7 +83,7 @@ typedef struct _NEGOTIATE_MESSAGE {
 	SECURITY_BUFFER WorkstationName;	/* RFC 1001 and ASCII */
 	/* SECURITY_BUFFER for version info not present since we
 	   do not set the version is present flag */
-	char DomainString[0];
+	char DomainString[];
 	/* followed by WorkstationString */
 } __attribute__((packed)) NEGOTIATE_MESSAGE, *PNEGOTIATE_MESSAGE;
 
@@ -135,7 +135,7 @@ typedef struct _AUTHENTICATE_MESSAGE {
 	__le32 NegotiateFlags;
 	/* SECURITY_BUFFER for version info not present since we
 	   do not set the version is present flag */
-	char UserString[0];
+	char UserString[];
 } __attribute__((packed)) AUTHENTICATE_MESSAGE, *PAUTHENTICATE_MESSAGE;
 
 /*
-- 
2.34.1

Re: [PATCH][next] cifs: Replace zero-length arrays with flexible-array members

[Kees Cook]

On Mon, Jan 09, 2023 at 07:39:00PM -0600, Gustavo A. R. Silva wrote:
> Zero-length arrays are deprecated[1] and we are moving towards
> adopting C99 flexible-array members instead. So, replace zero-length
> arrays in a couple of structures with flex-array members.
> 
> This helps with the ongoing efforts to tighten the FORTIFY_SOURCE
> routines on memcpy() and help us make progress towards globally
> enabling -fstrict-flex-arrays=3 [2].
> 
> Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays [1]
> Link: https://gcc.gnu.org/pipermail/gcc-patches/2022-October/602902.html [2]
> Link: https://github.com/KSPP/linux/issues/78
> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

Reviewed-by: Kees Cook <keescook@chromium.org>

-- 
Kees Cook

Re: [PATCH][next] cifs: Replace zero-length arrays with flexible-array members

[Steve French]

merged into cifs-2.6.git for-next

On Thu, Jan 12, 2023 at 4:52 PM Kees Cook <keescook@chromium.org> wrote:
>
> On Mon, Jan 09, 2023 at 07:39:00PM -0600, Gustavo A. R. Silva wrote:
> > Zero-length arrays are deprecated[1] and we are moving towards
> > adopting C99 flexible-array members instead. So, replace zero-length
> > arrays in a couple of structures with flex-array members.
> >
> > This helps with the ongoing efforts to tighten the FORTIFY_SOURCE
> > routines on memcpy() and help us make progress towards globally
> > enabling -fstrict-flex-arrays=3 [2].
> >
> > Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays [1]
> > Link: https://gcc.gnu.org/pipermail/gcc-patches/2022-October/602902.html [2]
> > Link: https://github.com/KSPP/linux/issues/78
> > Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
>
> Reviewed-by: Kees Cook <keescook@chromium.org>
>
> --
> Kees Cook



-- 
Thanks,

Steve