linux-kernel - Re: [BUG] char: pcmcia: a possible concurrency double-free bug in rx_alloc

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Date:   Mon, 7 Jan 2019 09:53:37 +0100
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Jia-Ju Bai <baijiaju1990@...il.com>
Cc:     arnd@...db.de, viro@...iv.linux.org.uk,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [BUG] char: pcmcia: a possible concurrency double-free bug in
 rx_alloc_buffers()

On Mon, Jan 07, 2019 at 04:12:22PM +0800, Jia-Ju Bai wrote:
> In drivers/char/pcmcia/synclink_cs.c, the functions mgslpc_open() and hdlcdev_open() can be concurrently executed.
> 
> hdlcdev_open
>   startup
>     claim_resources
>       rx_alloc_buffers
>         line 2641: kfree(info->rx_buf)
> 
> mgslpc_open
>   startup
>     claim_resources
>       rx_alloc_buffers
>         line 2641: kfree(info->rx_buf)
> 
> Thus, a possible concurrency double-free bug may occur.
> 
> This possible bug is found by a static analysis tool written by myself and my manual code review.

Care to send a patch to fix up this potential issue?

thanks,

greg k-h