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Message-ID: <CAK8P3a3A+CxJVt79ogxQn3NuRB01TsFchr-zu30E57xBut_=NQ@mail.gmail.com>
Date: Fri, 8 Oct 2021 09:02:14 +0200
From: Arnd Bergmann <arnd@...db.de>
To: Xiaolong Huang <butterflyhuangxx@...il.com>
Cc: Karsten Keil <isdn@...ux-pingi.de>,
David Miller <davem@...emloft.net>,
Arnd Bergmann <arnd@...db.de>,
Networking <netdev@...r.kernel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] isdn: cpai: check ctr->cnr to avoid array index out of bound
On Fri, Oct 8, 2021 at 8:58 AM Xiaolong Huang
<butterflyhuangxx@...il.com> wrote:
>
> The cmtp_add_connection() would add a cmtp session to a controller
> and run a kernel thread to process cmtp.
>
> __module_get(THIS_MODULE);
> session->task = kthread_run(cmtp_session, session, "kcmtpd_ctr_%d",
> session->num);
>
> During this process, the kernel thread would call detach_capi_ctr()
> to detach a register controller. if the controller
> was not attached yet, detach_capi_ctr() would
> trigger an array-index-out-bounds bug.
>
> [ 46.866069][ T6479] UBSAN: array-index-out-of-bounds in
> drivers/isdn/capi/kcapi.c:483:21
> [ 46.867196][ T6479] index -1 is out of range for type 'capi_ctr *[32]'
> [ 46.867982][ T6479] CPU: 1 PID: 6479 Comm: kcmtpd_ctr_0 Not tainted
> 5.15.0-rc2+ #8
> [ 46.869002][ T6479] Hardware name: QEMU Standard PC (i440FX + PIIX,
> 1996), BIOS 1.14.0-2 04/01/2014
> [ 46.870107][ T6479] Call Trace:
> [ 46.870473][ T6479] dump_stack_lvl+0x57/0x7d
> [ 46.870974][ T6479] ubsan_epilogue+0x5/0x40
> [ 46.871458][ T6479] __ubsan_handle_out_of_bounds.cold+0x43/0x48
> [ 46.872135][ T6479] detach_capi_ctr+0x64/0xc0
> [ 46.872639][ T6479] cmtp_session+0x5c8/0x5d0
> [ 46.873131][ T6479] ? __init_waitqueue_head+0x60/0x60
> [ 46.873712][ T6479] ? cmtp_add_msgpart+0x120/0x120
> [ 46.874256][ T6479] kthread+0x147/0x170
> [ 46.874709][ T6479] ? set_kthread_struct+0x40/0x40
> [ 46.875248][ T6479] ret_from_fork+0x1f/0x30
> [ 46.875773][ T6479]
>
> Signed-off-by: Xiaolong Huang <butterflyhuangxx@...il.com>
Acked-by: Arnd Bergmann <arnd@...db.de>
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