From: Mike Isely <isely@isely.net>
To: "Ricardo B. Marliere" <ricardo@marliere.net>
Cc: syzbot+621409285c4156a009b3@syzkaller.appspotmail.com,
Mauro Carvalho Chehab <mchehab@kernel.org>,
linux-kernel-mentees@lists.linuxfoundation.org,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-media@vger.kernel.org
Subject: Re: [PATCH] media: pvrusb2: fix use after free on context disconnection
Date: Sun, 15 Oct 2023 20:49:57 -0500 (CDT) [thread overview]
Message-ID: <5f652494-1e4f-4965-f9b7-0f2bf05f718f@isely.net> (raw)
In-Reply-To: <20231012230911.48113-2-ricardo@marliere.net>
Acked-by: Mike Isely <isely@pobox.com>
-Mike
On Thu, 12 Oct 2023, Ricardo B. Marliere wrote:
> Upon module load, a kthread is created targeting the
> pvr2_context_thread_func function, which may call pvr2_context_destroy
> and thus call kfree() on the context object. However, that might happen
> before the usb hub_event handler is able to notify the driver. This
> patch adds a sanity check before the invalid read reported by syzbot,
> within the context disconnection call stack.
>
> Fixes: e5be15c63804 ("V4L/DVB (7711): pvrusb2: Fix race on module unload")
> Reported-and-tested-by: syzbot+621409285c4156a009b3@syzkaller.appspotmail.com
> Closes: https://lore.kernel.org/all/000000000000a02a4205fff8eb92@google.com/
> Signed-off-by: Ricardo B. Marliere <ricardo@marliere.net>
> ---
> drivers/media/usb/pvrusb2/pvrusb2-context.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/media/usb/pvrusb2/pvrusb2-context.c b/drivers/media/usb/pvrusb2/pvrusb2-context.c
> index 14170a5d72b3..1764674de98b 100644
> --- a/drivers/media/usb/pvrusb2/pvrusb2-context.c
> +++ b/drivers/media/usb/pvrusb2/pvrusb2-context.c
> @@ -268,7 +268,8 @@ void pvr2_context_disconnect(struct pvr2_context *mp)
> {
> pvr2_hdw_disconnect(mp->hdw);
> mp->disconnect_flag = !0;
> - pvr2_context_notify(mp);
> + if (!pvr2_context_shutok())
> + pvr2_context_notify(mp);
> }
>
>
>
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prev parent reply other threads:[~2023-10-16 1:55 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-12 23:09 [PATCH] media: pvrusb2: fix use after free on context disconnection Ricardo B. Marliere
2023-10-16 1:49 ` Mike Isely [this message]
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