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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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| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
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| tools | ||
| usr | ||
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| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
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| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.