All of lore.kernel.org
 help / color / mirror / Atom feed
From: Dan Carpenter <error27@gmail.com>
To: Martin Kaiser <martin@kaiser.cx>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Larry Finger <Larry.Finger@lwfinger.net>,
	Phillip Potter <phil@philpotter.co.uk>,
	Michael Straube <straube.linux@gmail.com>,
	Pavel Skripkin <paskripkin@gmail.com>,
	linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] staging: r8188eu: fix NULL check for rcu pointer
Date: Tue, 31 Jan 2023 18:19:46 +0300	[thread overview]
Message-ID: <Y9kxkhmS+yEs85s1@kadam> (raw)
In-Reply-To: <20230131090057.241779-1-martin@kaiser.cx>

[ Resending because my email setup is crap and silently eats my out
  going mail. ]

On Tue, Jan 31, 2023 at 10:00:57AM +0100, Martin Kaiser wrote:
> Fix the NULL check for padapter->pnetdev->rx_handler_data.
> 
> The current code calls rcu_dereference while it holds the rcu read lock
> and checks the pointer after releasing the lock. An rcu pointer may only be
> used between calls to rcu_read_lock and rcu_read_unlock.
> 
> Replace the check with rcu_access_pointer. My understanding is that this
> function returns the value of the pointer and needs no locking. We can
> then check the pointer but we must not dereference it.
> 
> Signed-off-by: Martin Kaiser <martin@kaiser.cx>

This patch is fine but it's a clean up and not a fix.  The original code
doesn't dereference "br_port".  I guess the new code is faster and
especially if you have lockdep enabled, so maybe in that sense it is a
fix.

regards,
dan carpenter


  parent reply	other threads:[~2023-01-31 15:20 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-31  9:00 [PATCH] staging: r8188eu: fix NULL check for rcu pointer Martin Kaiser
2023-01-31 15:09 ` Greg Kroah-Hartman
2023-01-31 17:16   ` Martin Kaiser
2023-02-01  5:06     ` Dan Carpenter
2023-01-31 15:19 ` Dan Carpenter [this message]
2023-01-31 17:23   ` Martin Kaiser

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=Y9kxkhmS+yEs85s1@kadam \
    --to=error27@gmail.com \
    --cc=Larry.Finger@lwfinger.net \
    --cc=gregkh@linuxfoundation.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-staging@lists.linux.dev \
    --cc=martin@kaiser.cx \
    --cc=paskripkin@gmail.com \
    --cc=phil@philpotter.co.uk \
    --cc=straube.linux@gmail.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 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.