From: Greg KH <gregkh@linuxfoundation.org>
To: Anirudh Rayabharam <mail@anirudhrb.com>
Cc: "David S. Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
Oliver Neukum <oneukum@suse.com>,
Emil Renner Berthing <kernel@esmil.dk>,
Geert Uytterhoeven <geert@linux-m68k.org>,
Zheng Yongjun <zhengyongjun3@huawei.com>,
Rustam Kovhaev <rkovhaev@gmail.com>,
syzbot+c49fe6089f295a05e6f8@syzkaller.appspotmail.com,
linux-usb@vger.kernel.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] net: hso: fix null-ptr-deref during tty device unregistration
Date: Tue, 6 Apr 2021 16:05:03 +0200 [thread overview]
Message-ID: <YGxqj1ow9F7kWi98@kroah.com> (raw)
In-Reply-To: <20210406124402.20930-1-mail@anirudhrb.com>
On Tue, Apr 06, 2021 at 06:13:59PM +0530, Anirudh Rayabharam wrote:
> Multiple ttys try to claim the same the minor number causing a double
> unregistration of the same device. The first unregistration succeeds
> but the next one results in a null-ptr-deref.
>
> The get_free_serial_index() function returns an available minor number
> but doesn't assign it immediately. The assignment is done by the caller
> later. But before this assignment, calls to get_free_serial_index()
> would return the same minor number.
>
> Fix this by modifying get_free_serial_index to assign the minor number
> immediately after one is found to be and rename it to obtain_minor()
> to better reflect what it does. Similary, rename set_serial_by_index()
> to release_minor() and modify it to free up the minor number of the
> given hso_serial. Every obtain_minor() should have corresponding
> release_minor() call.
>
> Reported-by: syzbot+c49fe6089f295a05e6f8@syzkaller.appspotmail.com
> Tested-by: syzbot+c49fe6089f295a05e6f8@syzkaller.appspotmail.com
>
> Signed-off-by: Anirudh Rayabharam <mail@anirudhrb.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
next prev parent reply other threads:[~2021-04-06 14:05 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-06 12:43 [PATCH] net: hso: fix null-ptr-deref during tty device unregistration Anirudh Rayabharam
2021-04-06 14:05 ` Greg KH [this message]
2021-04-06 14:05 ` Greg KH
2021-04-06 23:39 ` David Miller
2021-04-07 18:11 ` Anirudh Rayabharam
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