linux-kernel - [PATCH v3] nfs: remove incorrect fallthrough label

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20200917214545.199463-1-ndesaulniers@google.com>
Date:   Thu, 17 Sep 2020 14:45:45 -0700
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     Trond Myklebust <trond.myklebust@...merspace.com>,
        Anna Schumaker <anna.schumaker@...app.com>
Cc:     "Gustavo A . R . Silva" <gustavo@...eddedor.com>,
        Joe Perches <joe@...ches.com>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        "Gustavo A . R . Silva" <gustavoars@...nel.org>,
        Miaohe Lin <linmiaohe@...wei.com>,
        Nathan Chancellor <natechancellor@...il.com>,
        Hongxiang Lou <louhongxiang@...wei.com>,
        linux-nfs@...r.kernel.org, linux-kernel@...r.kernel.org,
        clang-built-linux@...glegroups.com
Subject: [PATCH v3] nfs: remove incorrect fallthrough label

There is no case after the default from which to fallthrough to. Clang
will error in this case (unhelpfully without context, see link below)
and GCC will with -Wswitch-unreachable.

The previous commit should have just replaced the comment with a break
statement.

If we consider implicit fallthrough to be a design mistake of C, then
all case statements should be terminated with one of the following
statements:
* break
* continue
* return
* fallthrough
* goto
* (call of function with __attribute__(__noreturn__))

Fixes: 2a1390c95a69 ("nfs: Convert to use the preferred fallthrough macro")
Link: https://bugs.llvm.org/show_bug.cgi?id=47539
Acked-by: Gustavo A. R. Silva <gustavoars@...nel.org>
Reviewed-by: Gustavo A. R. Silva <gustavoars@...nel.org>
Reviewed-by: Miaohe Lin <linmiaohe@...wei.com>
Reviewed-by: Nathan Chancellor <natechancellor@...il.com>
Suggested-by: Joe Perches <joe@...ches.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@...gle.com>
---
Changes v3:
* update the commit message as per Joe.
* collect tags.

Changes v2:
* add break rather than no terminating statement as per Joe.
* add Joe's suggested by tag.
* add blurb about acceptable terminal statements.

 fs/nfs/super.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index d20326ee0475..eb2401079b04 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -889,7 +889,7 @@ static struct nfs_server *nfs_try_mount_request(struct fs_context *fc)
 		default:
 			if (rpcauth_get_gssinfo(flavor, &info) != 0)
 				continue;
-			fallthrough;
+			break;
 		}
 		dfprintk(MOUNT, "NFS: attempting to use auth flavor %u\n", flavor);
 		ctx->selected_flavor = flavor;
-- 
2.28.0.681.g6f77f65b4e-goog