From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BA67E16D320; Tue, 18 Jun 2024 12:55:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718715348; cv=none; b=GI8Wbz75tLBSXWrlw1ucsDS641tHeUQ6tR8CG4TLUMmUpA//ypkwjl8/T3g+lSTwRe3Km1i8q6lY4N2vQklMwCZz77ZOIZbw9Zhwu6RdKHA6M4qzDa7fOkn+hvsOvFTgrxdrHIjanVWl+gxPGX2CxB9YnTVkmJGwyTvW0FOygVw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718715348; c=relaxed/simple; bh=Wef/eK2PTgez+svjkcxyiVUCAo6nn0aNJn7F5NxDusw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=LFE7wLNmPGn+vlnRyQFZ0SgTR9VujeN5K8baxEFeECcb3Sv1NqMXVbkvOnLbGWHzCHIG0u5z1mW669JBT6AWTGB17lme/wogtvtEzLoopmFyS8o88zVv71YEV9d0rnr3aZp4RpRp3dD0IAF5ALo8o+oODJLGjHVt3Qq0qfduGYk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=PP/6Gfat; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="PP/6Gfat" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3D101C3277B; Tue, 18 Jun 2024 12:55:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1718715348; bh=Wef/eK2PTgez+svjkcxyiVUCAo6nn0aNJn7F5NxDusw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=PP/6GfatNlmT7vIAbglO6en7Df7FUECw6m4AS+fVWFLOYH/SOSVoss0/upxxEOP1y Nr/bFSYSs3LJz9LibrHUbm9Me02GPmfi1+348oJgX9EIb9v6EGfcRygYSojwCDkAA3 92oJvHny7pibgKRIOt8ccoxynqNLDYaSRBqf2SKk= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, "Gustavo A. R. Silva" , Chuck Lever , Sasha Levin Subject: [PATCH 5.10 247/770] UAPI: nfsfh.h: Replace one-element array with flexible-array member Date: Tue, 18 Jun 2024 14:31:40 +0200 Message-ID: <20240618123416.811709579@linuxfoundation.org> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20240618123407.280171066@linuxfoundation.org> References: <20240618123407.280171066@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 5.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Gustavo A. R. Silva [ Upstream commit c0a744dcaa29e9537e8607ae9c965ad936124a4d ] There is a regular need in the kernel to provide a way to declare having a dynamically sized set of trailing elements in a structure. Kernel code should always use “flexible array members”[1] for these cases. The older style of one-element or zero-length arrays should no longer be used[2]. Use an anonymous union with a couple of anonymous structs in order to keep userspace unchanged: $ pahole -C nfs_fhbase_new fs/nfsd/nfsfh.o struct nfs_fhbase_new { union { struct { __u8 fb_version_aux; /* 0 1 */ __u8 fb_auth_type_aux; /* 1 1 */ __u8 fb_fsid_type_aux; /* 2 1 */ __u8 fb_fileid_type_aux; /* 3 1 */ __u32 fb_auth[1]; /* 4 4 */ }; /* 0 8 */ struct { __u8 fb_version; /* 0 1 */ __u8 fb_auth_type; /* 1 1 */ __u8 fb_fsid_type; /* 2 1 */ __u8 fb_fileid_type; /* 3 1 */ __u32 fb_auth_flex[0]; /* 4 0 */ }; /* 0 4 */ }; /* 0 8 */ /* size: 8, cachelines: 1, members: 1 */ /* last cacheline: 8 bytes */ }; Also, this helps with the ongoing efforts to enable -Warray-bounds by fixing the following warnings: fs/nfsd/nfsfh.c: In function ‘nfsd_set_fh_dentry’: fs/nfsd/nfsfh.c:191:41: warning: array subscript 1 is above array bounds of ‘__u32[1]’ {aka ‘unsigned int[1]’} [-Warray-bounds] 191 | ntohl((__force __be32)fh->fh_fsid[1]))); | ~~~~~~~~~~~^~~ ./include/linux/kdev_t.h:12:46: note: in definition of macro ‘MKDEV’ 12 | #define MKDEV(ma,mi) (((ma) << MINORBITS) | (mi)) | ^~ ./include/uapi/linux/byteorder/little_endian.h:40:26: note: in expansion of macro ‘__swab32’ 40 | #define __be32_to_cpu(x) __swab32((__force __u32)(__be32)(x)) | ^~~~~~~~ ./include/linux/byteorder/generic.h:136:21: note: in expansion of macro ‘__be32_to_cpu’ 136 | #define ___ntohl(x) __be32_to_cpu(x) | ^~~~~~~~~~~~~ ./include/linux/byteorder/generic.h:140:18: note: in expansion of macro ‘___ntohl’ 140 | #define ntohl(x) ___ntohl(x) | ^~~~~~~~ fs/nfsd/nfsfh.c:191:8: note: in expansion of macro ‘ntohl’ 191 | ntohl((__force __be32)fh->fh_fsid[1]))); | ^~~~~ fs/nfsd/nfsfh.c:192:32: warning: array subscript 2 is above array bounds of ‘__u32[1]’ {aka ‘unsigned int[1]’} [-Warray-bounds] 192 | fh->fh_fsid[1] = fh->fh_fsid[2]; | ~~~~~~~~~~~^~~ fs/nfsd/nfsfh.c:192:15: warning: array subscript 1 is above array bounds of ‘__u32[1]’ {aka ‘unsigned int[1]’} [-Warray-bounds] 192 | fh->fh_fsid[1] = fh->fh_fsid[2]; | ~~~~~~~~~~~^~~ [1] https://en.wikipedia.org/wiki/Flexible_array_member [2] https://www.kernel.org/doc/html/v5.10/process/deprecated.html#zero-length-and-one-element-arrays Link: https://github.com/KSPP/linux/issues/79 Link: https://github.com/KSPP/linux/issues/109 Signed-off-by: Gustavo A. R. Silva Signed-off-by: Chuck Lever Signed-off-by: Sasha Levin --- include/uapi/linux/nfsd/nfsfh.h | 27 +++++++++++++++++++-------- 1 file changed, 19 insertions(+), 8 deletions(-) diff --git a/include/uapi/linux/nfsd/nfsfh.h b/include/uapi/linux/nfsd/nfsfh.h index ff0ca88b1c8f6..427294dd56a1b 100644 --- a/include/uapi/linux/nfsd/nfsfh.h +++ b/include/uapi/linux/nfsd/nfsfh.h @@ -64,13 +64,24 @@ struct nfs_fhbase_old { * in include/linux/exportfs.h for currently registered values. */ struct nfs_fhbase_new { - __u8 fb_version; /* == 1, even => nfs_fhbase_old */ - __u8 fb_auth_type; - __u8 fb_fsid_type; - __u8 fb_fileid_type; - __u32 fb_auth[1]; -/* __u32 fb_fsid[0]; floating */ -/* __u32 fb_fileid[0]; floating */ + union { + struct { + __u8 fb_version_aux; /* == 1, even => nfs_fhbase_old */ + __u8 fb_auth_type_aux; + __u8 fb_fsid_type_aux; + __u8 fb_fileid_type_aux; + __u32 fb_auth[1]; + /* __u32 fb_fsid[0]; floating */ + /* __u32 fb_fileid[0]; floating */ + }; + struct { + __u8 fb_version; /* == 1, even => nfs_fhbase_old */ + __u8 fb_auth_type; + __u8 fb_fsid_type; + __u8 fb_fileid_type; + __u32 fb_auth_flex[]; /* flexible-array member */ + }; + }; }; struct knfsd_fh { @@ -97,7 +108,7 @@ struct knfsd_fh { #define fh_fsid_type fh_base.fh_new.fb_fsid_type #define fh_auth_type fh_base.fh_new.fb_auth_type #define fh_fileid_type fh_base.fh_new.fb_fileid_type -#define fh_fsid fh_base.fh_new.fb_auth +#define fh_fsid fh_base.fh_new.fb_auth_flex /* Do not use, provided for userspace compatiblity. */ #define fh_auth fh_base.fh_new.fb_auth -- 2.43.0