From: Viacheslav Dubeyko <slava@dubeyko.com>
To: "Pan Bian" <bianpan2016@163.com>, "Joe Perches" <joe@perches.com>,
"Ernesto A. Fernández" <ernesto.mnd.fernandez@gmail.com>,
"Andrew Morton" <akpm@linux-foundation.org>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] hfs: do not free node before using
Date: Fri, 23 Nov 2018 16:51:49 -0800 [thread overview]
Message-ID: <1543020709.12764.3.camel@dubeyko.com> (raw)
In-Reply-To: <1542963889-128825-1-git-send-email-bianpan2016@163.com>
On Fri, 2018-11-23 at 17:04 +0800, Pan Bian wrote:
> The function hfs_bmap_free frees node via hfs_bnode_put(node).
> However,
> it then reads node->this when dumping error message on an error path,
> which may result in a use-after-free bug. This patch frees node only
> when it is never used.
>
> Fixes: d614267329f("hfs/hfsplus: convert printks to pr_<level>")
>
> Signed-off-by: Pan Bian <bianpan2016@163.com>
> ---
> fs/hfs/btree.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/fs/hfs/btree.c b/fs/hfs/btree.c
> index 98b96ff..19017d2 100644
> --- a/fs/hfs/btree.c
> +++ b/fs/hfs/btree.c
> @@ -338,13 +338,14 @@ void hfs_bmap_free(struct hfs_bnode *node)
>
> nidx -= len * 8;
> i = node->next;
> - hfs_bnode_put(node);
> if (!i) {
> /* panic */;
> pr_crit("unable to free bnode %u. bmap not
> found!\n",
> node->this);
What's about simply to store node->this into the local variable in the
beginning of the cycle? In this case, it is possible to use the node ID
in the pr_crit() and to use the hfs_bnode_put(node) in the same place
without to use it twice. What do you think?
Thanks,
Vyacheslav Dubeyko.
> + hfs_bnode_put(node);
> return;
> }
> + hfs_bnode_put(node);
> node = hfs_bnode_find(tree, i);
> if (IS_ERR(node))
> return;
next prev parent reply other threads:[~2018-11-24 0:52 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-23 9:04 [PATCH] hfs: do not free node before using Pan Bian
2018-11-23 12:59 ` Joe Perches
2018-11-24 0:51 ` Viacheslav Dubeyko [this message]
2018-11-24 1:54 ` PanBian
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