All of lore.kernel.org
 help / color / mirror / Atom feed
From: Christian Brauner <brauner@kernel.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Christian Brauner <brauner@kernel.org>,
	Kees Cook <keescook@chromium.org>,
	linux-kernel@vger.kernel.org
Subject: [PATCH] pid: use struct_size_t() helper
Date: Sat,  1 Jul 2023 08:44:44 +0200	[thread overview]
Message-ID: <20230701-antrieb-rundbau-4b30efb507b2@brauner> (raw)
In-Reply-To: <202306300950.2BE7567101@keescook>

Before commit d67790ddf021 ("overflow: Add struct_size_t() helper") only
struct_size() existed, which expects a valid pointer instance containing
the flexible array.

However, when we determine the default struct pid allocation size for
the associated kmem cache of a pid namespace we need to take the nesting
depth of the pid namespace into account without an variable instance
necessarily being available.

In commit b69f0aeb0689 ("pid: Replace struct pid 1-element array with
flex-array") we used to handle this the old fashioned way and cast NULL
to a struct pid pointer type. However, we do apparently have a dedicated
struct_size_t() helper for exactly this case. So switch to that.

Suggested-by: Kees Cook <keescook@chromium.org>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
---
 kernel/pid.c           | 2 +-
 kernel/pid_namespace.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/pid.c b/kernel/pid.c
index 8bce3aebc949..6a1d23a11026 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -657,7 +657,7 @@ void __init pid_idr_init(void)
 	idr_init(&init_pid_ns.idr);
 
 	init_pid_ns.pid_cachep = kmem_cache_create("pid",
-			struct_size((struct pid *)NULL, numbers, 1),
+			struct_size_t(struct pid, numbers, 1),
 			__alignof__(struct pid),
 			SLAB_HWCACHE_ALIGN | SLAB_PANIC | SLAB_ACCOUNT,
 			NULL);
diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
index 70a929784a5d..0bf44afe04dd 100644
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c
@@ -48,7 +48,7 @@ static struct kmem_cache *create_pid_cachep(unsigned int level)
 		return kc;
 
 	snprintf(name, sizeof(name), "pid_%u", level + 1);
-	len = struct_size((struct pid *)NULL, numbers, level + 1);
+	len = struct_size_t(struct pid, numbers, level + 1);
 	mutex_lock(&pid_caches_mutex);
 	/* Name collision forces to do allocation under mutex. */
 	if (!*pkc)

base-commit: a507db1d8fdc39802415e4d2ef6d1aecd67927fa
-- 
2.34.1


  parent reply	other threads:[~2023-07-01  6:52 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-06-28 10:37 [GIT PULL] pid: use flex array Christian Brauner
2023-06-29 23:52 ` Linus Torvalds
2023-06-30  6:51   ` Christian Brauner
2023-06-30  7:12     ` Linus Torvalds
2023-06-30  8:04       ` Christian Brauner
2023-06-30 11:21         ` David Laight
2023-06-30 16:01           ` Linus Torvalds
2023-06-30 16:59         ` Kees Cook
2023-07-01  6:27           ` Christian Brauner
2023-07-01  6:44           ` Christian Brauner [this message]
2023-07-01 15:28             ` [PATCH] pid: use struct_size_t() helper Linus Torvalds

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20230701-antrieb-rundbau-4b30efb507b2@brauner \
    --to=brauner@kernel.org \
    --cc=keescook@chromium.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=torvalds@linux-foundation.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.