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Date: Fri, 28 Aug 2026 08:01:19 +0200
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Farhad Alemi <farhad.alemi@berkeley.edu>
Cc: Peter Chen <peter.chen@kernel.org>, falemi@asu.edu,
	linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [BUG] ci_hdrc_add_device -- KASAN slab-out-of-bounds reading a
 FOREIGN device's platform_data
Message-ID: <2026082846-lethargic-ability-93dd@gregkh>
References: <CA+0ovCi63OBqOySpNgU5xND840CDhi3B1dp1QsxhmcOOo-7w1w@mail.gmail.com>
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In-Reply-To: <CA+0ovCi63OBqOySpNgU5xND840CDhi3B1dp1QsxhmcOOo-7w1w@mail.gmail.com>

On Thu, Aug 27, 2026 at 10:34:56PM -0700, Farhad Alemi wrote:
> Hello,
> 
> As part of the kernel research at ASU's SEFCOM
> lab, we hit the crash below. Crash reports can be found here:
> 
>   https://github.com/farhad-alemi/public_bug_reports/tree/main/150-usb-chipidea-foreign-platform_data-oob/
> 
>   BUG: KASAN: slab-out-of-bounds in ci_hdrc_add_device+0xb76/0xd10
>   Read of size 4 at addr ffff88810e9061c8 by task repro/9505
>   Call Trace:
>    ci_hdrc_add_device+0xb76/0xd10
>    ci_hdrc_usb2_probe+0x22d/0x370
>    platform_probe+0xf9/0x190
>    really_probe+0x267/0xaf0
>    __driver_probe_device+0x1e2/0x350
>    device_driver_attach+0xe0/0x1d0
>    bind_store+0x1d0/0x220
>    kernfs_fop_write_iter+0x3af/0x540
>    vfs_write+0x61d/0xb90
>    ksys_write+0x150/0x270
> 
> Our reproducer.c is available upon request.
> 
> Happy to test a patch if that would help.

Please send such a patch.

But again, stop messing around with root-only sysfs files without
understanding that you get to keep the broken pieces of the kernel if
you touch them :)

thanks,

greg k-h