From: Song Liu <song@kernel.org>
To: Xiaomeng Tong <xiam0nd.tong@gmail.com>
Cc: rgoldwyn@suse.com, Guoqing Jiang <guoqing.jiang@linux.dev>,
linux-raid <linux-raid@vger.kernel.org>,
open list <linux-kernel@vger.kernel.org>,
stable@vger.kernel.org
Subject: Re: [PATCH v2] md: fix an incorrect NULL check in sync_sbs
Date: Thu, 7 Apr 2022 17:36:48 -0700 [thread overview]
Message-ID: <CAPhsuW6S=PJsgVR=OkObMvs9uJ2QA3LFe+ZH8XtEyKRFh7XxHA@mail.gmail.com> (raw)
In-Reply-To: <20220328081127.26148-1-xiam0nd.tong@gmail.com>
On Mon, Mar 28, 2022 at 1:11 AM Xiaomeng Tong <xiam0nd.tong@gmail.com> wrote:
>
> The bug is here:
> if (!rdev)
>
> The list iterator value 'rdev' will *always* be set and non-NULL
> by rdev_for_each(), so it is incorrect to assume that the iterator
> value will be NULL if the list is empty or no element found.
> Otherwise it will bypass the NULL check and lead to invalid memory
> access passing the check.
>
> To fix the bug, use a new variable 'iter' as the list iterator,
> while using the original variable 'pdev' as a dedicated pointer to
s/pdev/rdev/
> point to the found element.
>
> Cc: stable@vger.kernel.org
> Fixes: 2aa82191ac36c ("md-cluster: Perform a lazy update")
"Fixes" should use a hash of 12 characters (13 given here). Did
checkpatch.pl complain about it?
> Acked-by: Guoqing Jiang <guoqing.jiang@linux.dev>
> Signed-off-by: Xiaomeng Tong <xiam0nd.tong@gmail.com>
> ---
>
> changes since v1:
> - rephrase the subject (Guoqing Jiang)
> - add Acked-by: for Guoqing Jiang
> v1:https://lore.kernel.org/lkml/20220327080002.11923-1-xiam0nd.tong@gmail.com/
>
> ---
> drivers/md/md.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index 4d38bd7dadd6..7476fc204172 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -2629,14 +2629,16 @@ static void sync_sbs(struct mddev *mddev, int nospares)
>
> static bool does_sb_need_changing(struct mddev *mddev)
> {
> - struct md_rdev *rdev;
> + struct md_rdev *rdev = NULL, *iter;
> struct mdp_superblock_1 *sb;
> int role;
>
> /* Find a good rdev */
> - rdev_for_each(rdev, mddev)
> - if ((rdev->raid_disk >= 0) && !test_bit(Faulty, &rdev->flags))
> + rdev_for_each(iter, mddev)
> + if ((iter->raid_disk >= 0) && !test_bit(Faulty, &iter->flags)) {
> + rdev = iter;
> break;
> + }
>
> /* No good device found. */
> if (!rdev)
> --
> 2.17.1
>
next prev parent reply other threads:[~2022-04-08 0:37 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-28 8:11 [PATCH v2] md: fix an incorrect NULL check in sync_sbs Xiaomeng Tong
2022-04-08 0:36 ` Song Liu [this message]
2022-04-08 8:39 ` Xiaomeng Tong
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