netdev - Re: [PATCH net] net: qmi_wwan: fix Oops while disconnecting

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 25 Jun 2012 09:24:43 +0200
From:	Bjørn Mork <bjorn@...k.no>
To:	Ming Lei <tom.leiming@...il.com>
Cc:	Oliver Neukum <oliver@...kum.org>, netdev@...r.kernel.org,
	linux-usb@...r.kernel.org,
	Marius Bjørnstad Kotsbak 
	<marius.kotsbak@...il.com>
Subject: Re: [PATCH net] net: qmi_wwan: fix Oops while disconnecting

[I don't have anything more to add to the generic usbnet discussion, but
 want to comment on the qmi_wwan issues]

Ming Lei <tom.leiming@...il.com> writes:

> Also, the clear of intfdata may not be observed in .manage_power
> since usb_set_intfdata(, NULL) may be completed after the lock wdm_mutex
> operation.

True, but irrelevant.  The pointer is either valid or NULL.  We don't
need to care about synchronizing the exact time it is set to NULL.

The locking in cdc-wdm will ensure that the pointer is valid while it is
in use by .manage_power, because usbnet_disconnect is prevented from
continuing with free_netdev() while any caller of .manage_power is
running.

> So it is only the sync mechanism that  works on the race even the check is
> added in the patch.  Putting usb_set_intfdata(, NULL) after driver_info->unbind
> should be OK, and it is a general solution for the problem.

There is no problem wrt qmi_wwan and intfdata as long as the NULL test
is added to .manage_power.

Bjørn
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html