NFSD: Avoid clashing function prototypes
When built with Control Flow Integrity, function prototypes between caller and function declaration must match. These mismatches are visible at compile time with the new -Wcast-function-type-strict in Clang[1]. There were 97 warnings produced by NFS. For example: fs/nfsd/nfs4xdr.c:2228:17: warning: cast from '__be32 (*)(struct nfsd4_compoundargs *, struct nfsd4_access *)' (aka 'unsigned int (*)(struct nfsd4_compoundargs *, struct nfsd4_access *)') to 'nfsd4_dec' (aka 'unsigned int (*)(struct nfsd4_compoundargs *, void *)') converts to incompatible function type [-Wcast-function-type-strict] [OP_ACCESS] = (nfsd4_dec)nfsd4_decode_access, ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The enc/dec callbacks were defined as passing "void *" as the second argument, but were being implicitly cast to a new type. Replace the argument with union nfsd4_op_u, and perform explicit member selection in the function body. There are no resulting binary differences. Changes were made mechanically using the following Coccinelle script, with minor by-hand fixes for members that didn't already match their existing argument name: @find@ identifier func; type T, opsT; identifier ops, N; @@ opsT ops[] = { [N] = (T) func, }; @already_void@ identifier find.func; identifier name; @@ func(..., -void +union nfsd4_op_u *name) { ... } @proto depends on !already_void@ identifier find.func; type T; identifier name; position p; @@ func@p(..., T name ) { ... } @script:python get_member@ type_name << proto.T; member; @@ coccinelle.member = cocci.make_ident(type_name.split("_", 1)[1].split(' ',1)[0]) @convert@ identifier find.func; type proto.T; identifier proto.name; position proto.p; identifier get_member.member; @@ func@p(..., - T name + union nfsd4_op_u *u ) { + T name = &u->member; ... } @cast@ identifier find.func; type T, opsT; identifier ops, N; @@ opsT ops[] = { [N] = - (T) func, }; Cc: Chuck Lever <chuck.lever@oracle.com> Cc: Jeff Layton <jlayton@kernel.org> Cc: Gustavo A. R. Silva <gustavoars@kernel.org> Cc: linux-nfs@vger.kernel.org Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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