linux-kernel - Re: [PATCH v2 1/2] lkdtm: replace SCSI_DISPATCH_CMD with SCSI_QUEUE

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Message-ID: <202108182010.BB18020B8@keescook>
Date:   Wed, 18 Aug 2021 20:10:27 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Kevin Mitchell <kevmitch@...sta.com>
Cc:     linux-scsi@...r.kernel.org, Christoph Hellwig <hch@....de>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Akinobu Mita <akinobu.mita@...il.com>,
        Jonathan Corbet <corbet@....net>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Hannes Reinecke <hare@...e.de>,
        Bart Van Assche <bvanassche@....org>,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/2] lkdtm: replace SCSI_DISPATCH_CMD with
 SCSI_QUEUE_RQ

On Wed, Aug 18, 2021 at 07:29:39PM -0700, Kevin Mitchell wrote:
> When scsi_dispatch_cmd was moved to scsi_lib.c and made static, some
> compilers (i.e., at least gcc 8.4.0) decided to compile this
> inline. This is a problem for lkdtm.ko, which inserted a kprobe
> on this function for the SCSI_DISPATCH_CMD crashpoint.
> 
> Move this crashpoint one function up the call chain to
> scsi_queue_rq. Though this is also a static function, it should never be
> inlined because it is assigned as a structure entry. Therefore,
> kprobe_register should always be able to find it.
> 
> Fixes: 82042a2cdb55 ("scsi: move scsi_dispatch_cmd to scsi_lib.c")
> Signed-off-by: Kevin Mitchell <kevmitch@...sta.com>

Thanks!

Acked-by: Kees Cook <keescook@...omium.org>

-Kees

> ---
>  Documentation/fault-injection/provoke-crashes.rst | 2 +-
>  drivers/misc/lkdtm/core.c                         | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/fault-injection/provoke-crashes.rst b/Documentation/fault-injection/provoke-crashes.rst
> index a20ba5d93932..18de17354206 100644
> --- a/Documentation/fault-injection/provoke-crashes.rst
> +++ b/Documentation/fault-injection/provoke-crashes.rst
> @@ -29,7 +29,7 @@ recur_count
>  cpoint_name
>  	Where in the kernel to trigger the action. It can be
>  	one of INT_HARDWARE_ENTRY, INT_HW_IRQ_EN, INT_TASKLET_ENTRY,
> -	FS_DEVRW, MEM_SWAPOUT, TIMERADD, SCSI_DISPATCH_CMD,
> +	FS_DEVRW, MEM_SWAPOUT, TIMERADD, SCSI_QUEUE_RQ,
>  	IDE_CORE_CP, or DIRECT
>  
>  cpoint_type
> diff --git a/drivers/misc/lkdtm/core.c b/drivers/misc/lkdtm/core.c
> index 9dda87c6b54a..016cb0b150fc 100644
> --- a/drivers/misc/lkdtm/core.c
> +++ b/drivers/misc/lkdtm/core.c
> @@ -82,7 +82,7 @@ static struct crashpoint crashpoints[] = {
>  	CRASHPOINT("FS_DEVRW",		 "ll_rw_block"),
>  	CRASHPOINT("MEM_SWAPOUT",	 "shrink_inactive_list"),
>  	CRASHPOINT("TIMERADD",		 "hrtimer_start"),
> -	CRASHPOINT("SCSI_DISPATCH_CMD",	 "scsi_dispatch_cmd"),
> +	CRASHPOINT("SCSI_QUEUE_RQ",	 "scsi_queue_rq"),
>  	CRASHPOINT("IDE_CORE_CP",	 "generic_ide_ioctl"),
>  #endif
>  };
> -- 
> 2.32.0
> 

-- 
Kees Cook