From: Guenter Roeck <linux@roeck-us.net>
To: Zou Wei <zou_wei@huawei.com>
Cc: wim@linux-watchdog.org, vz@mleia.com,
linux-watchdog@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH -next] watchdog: Fix possible use-after-free by calling del_timer_sync()
Date: Wed, 12 May 2021 07:06:36 -0700 [thread overview]
Message-ID: <20210512140636.GK1333995@roeck-us.net> (raw)
In-Reply-To: <1620802676-19701-1-git-send-email-zou_wei@huawei.com>
On Wed, May 12, 2021 at 02:57:56PM +0800, Zou Wei wrote:
> This driver's remove path calls del_timer(). However, that function
> does not wait until the timer handler finishes. This means that the
> timer handler may still be running after the driver's remove function
> has finished, which would result in a use-after-free.
>
> Fix by calling del_timer_sync(), which makes sure the timer handler
> has finished, and unable to re-schedule itself.
>
> Reported-by: Hulk Robot <hulkci@huawei.com>
> Signed-off-by: Zou Wei <zou_wei@huawei.com>
If you have more of those, _please_ submit them together to save review time.
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Guenter
> ---
> drivers/watchdog/lpc18xx_wdt.c | 2 +-
> drivers/watchdog/w83877f_wdt.c | 2 +-
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/watchdog/lpc18xx_wdt.c b/drivers/watchdog/lpc18xx_wdt.c
> index 78cf11c..60b6d74 100644
> --- a/drivers/watchdog/lpc18xx_wdt.c
> +++ b/drivers/watchdog/lpc18xx_wdt.c
> @@ -292,7 +292,7 @@ static int lpc18xx_wdt_remove(struct platform_device *pdev)
> struct lpc18xx_wdt_dev *lpc18xx_wdt = platform_get_drvdata(pdev);
>
> dev_warn(&pdev->dev, "I quit now, hardware will probably reboot!\n");
> - del_timer(&lpc18xx_wdt->timer);
> + del_timer_sync(&lpc18xx_wdt->timer);
>
> return 0;
> }
> diff --git a/drivers/watchdog/w83877f_wdt.c b/drivers/watchdog/w83877f_wdt.c
> index 5772cc5..f265086 100644
> --- a/drivers/watchdog/w83877f_wdt.c
> +++ b/drivers/watchdog/w83877f_wdt.c
> @@ -166,7 +166,7 @@ static void wdt_startup(void)
> static void wdt_turnoff(void)
> {
> /* Stop the timer */
> - del_timer(&timer);
> + del_timer_sync(&timer);
>
> wdt_change(WDT_DISABLE);
>
> --
> 2.6.2
>
next prev parent reply other threads:[~2021-05-12 14:06 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-12 6:57 [PATCH -next] watchdog: Fix possible use-after-free by calling del_timer_sync() Zou Wei
2021-05-12 14:06 ` Guenter Roeck [this message]
2021-05-13 2:01 ` Samuel Zou
2021-05-12 17:04 ` Vladimir Zapolskiy
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=20210512140636.GK1333995@roeck-us.net \
--to=linux@roeck-us.net \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-watchdog@vger.kernel.org \
--cc=vz@mleia.com \
--cc=wim@linux-watchdog.org \
--cc=zou_wei@huawei.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).