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From: James Smart <james.smart@broadcom.com>
To: Greg KH <greg@kroah.com>
Cc: Kees Cook <keescook@chromium.org>, Willy Tarreau <w@1wt.eu>,
	Silvio Cesare <silvio.cesare@gmail.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Dick Kennedy <dick.kennedy@broadcom.com>,
	Dan Carpenter <dan.carpenter@oracle.com>,
	Will Deacon <will.deacon@arm.com>
Subject: Re: [PATCH 5/8] scsi: lpfc: change snprintf to scnprintf for possible overflow
Date: Wed, 20 Mar 2019 13:27:02 -0700	[thread overview]
Message-ID: <d23fb974-2486-a138-4aae-3575f730c4fd@broadcom.com> (raw)
In-Reply-To: <20190320173951.GA27003@kroah.com>

On 3/20/2019 10:39 AM, Greg KH wrote:
> On Tue, Jan 15, 2019 at 02:41:17PM -0800, James Smart wrote:
>> On 1/14/2019 5:15 PM, Kees Cook wrote:
>>> On Sat, Jan 12, 2019 at 7:29 AM Willy Tarreau<w@1wt.eu>  wrote:
>>>> From: Silvio Cesare<silvio.cesare@gmail.com>
>>>>
>>>> Change snprintf to scnprintf. There are generally two cases where using
>>>> snprintf causes problems.
>>>>
>>>> 1) Uses of size += snprintf(buf, SIZE - size, fmt, ...)
>>>> In this case, if snprintf would have written more characters than what the
>>>> buffer size (SIZE) is, then size will end up larger than SIZE. In later
>>>> uses of snprintf, SIZE - size will result in a negative number, leading
>>>> to problems. Note that size might already be too large by using
>>>> size = snprintf before the code reaches a case of size += snprintf.
>>>>
>>>> 2) If size is ultimately used as a length parameter for a copy back to user
>>>> space, then it will potentially allow for a buffer overflow and information
>>>> disclosure when size is greater than SIZE. When the size is used to index
>>>> the buffer directly, we can have memory corruption. This also means when
>>>> size = snprintf... is used, it may also cause problems since size may become
>>>> large.  Copying to userspace is mitigated by the HARDENED_USERCOPY kernel
>>>> configuration.
>>>>
>>>> The solution to these issues is to use scnprintf which returns the number of
>>>> characters actually written to the buffer, so the size variable will never
>>>> exceed SIZE.
>>>>
>>>> Signed-off-by: Silvio Cesare<silvio.cesare@gmail.com>
>>>> Cc: James Smart<james.smart@broadcom.com>
>>>> Cc: Dick Kennedy<dick.kennedy@broadcom.com>
>>>> Cc: Dan Carpenter<dan.carpenter@oracle.com>
>>>> Cc: Kees Cook<keescook@chromium.org>
>>>> Cc: Will Deacon<will.deacon@arm.com>
>>>> Cc: Greg KH<greg@kroah.com>
>>>> Signed-off-by: Willy Tarreau<w@1wt.eu>
>>> I think this needs Cc: stable.
>>>
>>> Reviewed-by: Kees Cook<keescook@chromium.org>
>>>
>>> -Kees
>>>
>>
>> Reviewed-by:  James Smart <james.smart@broadcom.com>
> What ever happened to this patch?  Did it get dropped somehow?
>
> thanks,
>
> greg k-h

I assume it wasn't pulled in by the scsi maintainers. I'll go ping them.

-- james


  reply	other threads:[~2019-03-20 20:27 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-12 15:28 [PATCH 1/8] lkdtm: change snprintf to scnprintf for possible overflow Willy Tarreau
2019-01-12 15:28 ` [PATCH 2/8] libertas: " Willy Tarreau
2019-01-15  1:09   ` Kees Cook
2019-01-15  5:55   ` Kalle Valo
2019-01-15 20:35     ` Willy Tarreau
2019-01-16 16:40       ` Kalle Valo
2019-01-16 17:02         ` Willy Tarreau
2019-01-12 15:28 ` [PATCH 3/8] ocfs2: " Willy Tarreau
2019-01-15  1:14   ` Kees Cook
2019-01-12 15:28 ` [PATCH 4/8] ASoC: " Willy Tarreau
2019-01-15  1:13   ` Kees Cook
2019-01-15  1:25   ` Nicolin Chen
2019-01-15  3:18     ` Willy Tarreau
2019-01-12 15:28 ` [PATCH 5/8] scsi: lpfc: " Willy Tarreau
2019-01-15  1:15   ` Kees Cook
2019-01-15 22:41     ` James Smart
2019-03-20 17:39       ` Greg KH
2019-03-20 20:27         ` James Smart [this message]
2019-03-21  0:41         ` James Smart
2019-01-12 15:28 ` [PATCH 6/8] ASoC: intel: skylake: " Willy Tarreau
2019-01-15  1:12   ` Kees Cook
2019-01-16 18:41   ` Kees Cook
2019-01-16 19:35     ` Pierre-Louis Bossart
2019-01-16 19:51       ` Kees Cook
2019-01-12 15:28 ` [PATCH 7/8] ASoC: dapm: " Willy Tarreau
2019-01-14 14:56   ` Mark Brown
2019-01-15  3:16     ` Willy Tarreau
2019-01-15 15:44       ` Mark Brown
2019-01-15 15:55         ` Willy Tarreau
2019-01-12 15:28 ` [PATCH 8/8] spi: dw: " Willy Tarreau
2019-01-15  1:09   ` Kees Cook
2019-01-15  1:02 ` [PATCH 1/8] lkdtm: " Kees Cook
2019-01-15  1:07   ` Kees Cook
2019-01-15  3:12   ` Willy Tarreau
2019-01-15 20:47 ` Kees Cook
2019-01-18 13:06   ` Greg KH

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