[PATCH] usb: gadget: f_mass_storage: common->curlun could be NULL

[PATCH] usb: gadget: f_mass_storage: common->curlun could be NULL

[Christoph Fritz]

This patch adds a NULL check for common->curlun in case of an unknown_cmnd
in do_scsi_command(). 

Signed-off-by: Christoph Fritz <chf.fritz@googlemail.com>
---
 drivers/usb/gadget/f_mass_storage.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/drivers/usb/gadget/f_mass_storage.c b/drivers/usb/gadget/f_mass_storage.c
index c39d588..0e42027 100644
--- a/drivers/usb/gadget/f_mass_storage.c
+++ b/drivers/usb/gadget/f_mass_storage.c
@@ -2184,7 +2184,8 @@ unknown_cmnd:
 		reply = check_command(common, common->cmnd_size,
 				      DATA_DIR_UNKNOWN, 0xff, 0, unknown);
 		if (reply = 0) {
-			common->curlun->sense_data = SS_INVALID_COMMAND;
+			if (common->curlun)
+				common->curlun->sense_data = SS_INVALID_COMMAND;
 			reply = -EINVAL;
 		}
 		break;
-- 
1.7.2.5

Re: [PATCH] usb: gadget: f_mass_storage: common->curlun could be NULL

[Michal Nazarewicz]

On Tue, 29 Nov 2011 22:00:16 +0100, Christoph Fritz <chf.fritz@googlemail.com> wrote:
> This patch adds a NULL check for common->curlun in case of an unknown_cmnd
> in do_scsi_command().

Did you actually encountered it? check_command() should set curlun, shouldn't it?

After calling check_command() curlun may be NULL only in two situations:
1. check_command() returned negative error code, or
2. we're dealing with INQUIRY or REQUEST_SENSE command.

In the first case, the line in question is not executed at all because of “if
(reply = 0)” check.

In the second case, we won't reach “unknown_cmnd” label because the two commands
have their own case labels and do not perform a goto.

So as far as I can see, common->curlun cannot be NULL in the place this patch
is fixing.

> Signed-off-by: Christoph Fritz <chf.fritz@googlemail.com>
> ---
>  drivers/usb/gadget/f_mass_storage.c |    3 ++-
>  1 files changed, 2 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/usb/gadget/f_mass_storage.c b/drivers/usb/gadget/f_mass_storage.c
> index c39d588..0e42027 100644
> --- a/drivers/usb/gadget/f_mass_storage.c
> +++ b/drivers/usb/gadget/f_mass_storage.c
> @@ -2184,7 +2184,8 @@ unknown_cmnd:
>  		reply = check_command(common, common->cmnd_size,
>  				      DATA_DIR_UNKNOWN, 0xff, 0, unknown);
>  		if (reply = 0) {
> -			common->curlun->sense_data = SS_INVALID_COMMAND;
> +			if (common->curlun)
> +				common->curlun->sense_data = SS_INVALID_COMMAND;
>  			reply = -EINVAL;
>  		}
>  		break;

-- 
Best regards,                                         _     _
.o. | Liege of Serenely Enlightened Majesty of      o' \,=./ `o
..o | Computer Science,  Michał “mina86” Nazarewicz    (o o)
ooo +----<email/xmpp: mpn@google.com>--------------ooO--(_)--Ooo--