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To: Alan Stern <stern@rowland.harvard.edu>
Cc: Greg KH <gregkh@linuxfoundation.org>,
        syzbot
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        bvanassche@acm.org, emilne@redhat.com, linux-kernel@vger.kernel.org,
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        usb-storage@lists.one-eyed-alien.net
Subject: Re: [PATCH] USB: usb-storage: Prevent divide-by-0 error in
 isd200_ata_command
From: "Martin K. Petersen" <martin.petersen@oracle.com>
Organization: Oracle Corporation
Message-ID: <yq1frxazrgx.fsf@ca-mkp.ca.oracle.com>
References: <380909e4-6e0a-402f-b3ac-de07e520c910@rowland.harvard.edu>
	<000000000000102fe606127a67f6@google.com>
	<b1e605ea-333f-4ac0-9511-da04f411763e@rowland.harvard.edu>
Date: Thu, 29 Feb 2024 20:11:35 -0500
In-Reply-To: <b1e605ea-333f-4ac0-9511-da04f411763e@rowland.harvard.edu> (Alan
	Stern's message of "Thu, 29 Feb 2024 14:30:06 -0500")
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Alan,

> The isd200 sub-driver in usb-storage uses the HEADS and SECTORS values
> in the ATA ID information to calculate cylinder and head values when
> creating a CDB for READ or WRITE commands. The calculation involves
> division and modulus operations, which will cause a crash if either of
> these values is 0. While this never happens with a genuine device, it
> could happen with a flawed or subversive emulation, as reported by the
> syzbot fuzzer.

Looks good to me.

Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>

-- 
Martin K. Petersen	Oracle Linux Engineering