netdev.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Salvatore Mesoraca <s.mesoraca16@gmail.com>
To: linux-kernel@vger.kernel.org
Cc: kernel-hardening@lists.openwall.com, netdev@vger.kernel.org,
	"David S. Miller" <davem@davemloft.net>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	David Rientjes <rientjes@google.com>,
	Elena Reshetova <elena.reshetova@intel.com>,
	Hans Liljestrand <ishkamiel@gmail.com>,
	Kees Cook <keescook@chromium.org>,
	Salvatore Mesoraca <s.mesoraca16@gmail.com>
Subject: [PATCH] net: llc: drop VLA in llc_sap_mcast()
Date: Sun, 11 Mar 2018 22:12:04 +0100	[thread overview]
Message-ID: <1520802724-17509-1-git-send-email-s.mesoraca16@gmail.com> (raw)

Avoid a VLA[1] by using a real constant expression instead of a variable.
The compiler should be able to optimize the original code and avoid using
an actual VLA. Anyway this change is useful because it will avoid a false
positive with -Wvla, it might also help the compiler generating better
code.

[1] https://lkml.org/lkml/2018/3/7/621

Signed-off-by: Salvatore Mesoraca <s.mesoraca16@gmail.com>
---
 net/llc/llc_sap.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/net/llc/llc_sap.c b/net/llc/llc_sap.c
index d90928f..a7f7b8f 100644
--- a/net/llc/llc_sap.c
+++ b/net/llc/llc_sap.c
@@ -394,8 +394,9 @@ static void llc_sap_mcast(struct llc_sap *sap,
 			  const struct llc_addr *laddr,
 			  struct sk_buff *skb)
 {
-	int i = 0, count = 256 / sizeof(struct sock *);
-	struct sock *sk, *stack[count];
+	int i = 0;
+	struct sock *sk;
+	struct sock *stack[256 / sizeof(struct sock *)];
 	struct llc_sock *llc;
 	struct hlist_head *dev_hb = llc_sk_dev_hash(sap, skb->dev->ifindex);
 
@@ -408,7 +409,7 @@ static void llc_sap_mcast(struct llc_sap *sap,
 			continue;
 
 		sock_hold(sk);
-		if (i < count)
+		if (i < ARRAY_SIZE(stack))
 			stack[i++] = sk;
 		else {
 			llc_do_mcast(sap, skb, stack, i);
-- 
1.9.1

             reply	other threads:[~2018-03-11 21:12 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-11 21:12 Salvatore Mesoraca [this message]
2018-03-12 15:14 ` [PATCH] net: llc: drop VLA in llc_sap_mcast() David Miller
2018-03-12 16:47   ` Salvatore Mesoraca

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=1520802724-17509-1-git-send-email-s.mesoraca16@gmail.com \
    --to=s.mesoraca16@gmail.com \
    --cc=davem@davemloft.net \
    --cc=elena.reshetova@intel.com \
    --cc=ishkamiel@gmail.com \
    --cc=keescook@chromium.org \
    --cc=kernel-hardening@lists.openwall.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=netdev@vger.kernel.org \
    --cc=paulmck@linux.vnet.ibm.com \
    --cc=rientjes@google.com \
    /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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).