Re: [PATCH] kobject: fix suppressing modalias in uevents delivered over netlink

From: Tariq Toukan
Date: Tue Dec 19 2017 - 10:41:21 EST

On 19/12/2017 11:12 AM, Eric Dumazet wrote:
On Tue, Dec 19, 2017 at 12:48 AM, Greg Kroah-Hartman
<gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
On Wed, Dec 13, 2017 at 03:21:22PM -0800, Dmitry Torokhov wrote:
The commit 4a336a23d619 ("kobject: copy env blob in one go") optimized
constructing uevent data for delivery over netlink by using the raw
environment buffer, instead of reconstructing it from individual
environment pointers. Unfortunately in doing so it broke suppressing
MODALIAS attribute for KOBJ_UNBIND events, as the code that suppressed this
attribute only adjusted the environment pointers, but left the buffer
itself alone. Let's fix it by making sure the offending attribute is
obliterated form the buffer as well.

Reported-by: Tariq Toukan <tariqt@xxxxxxxxxxxx>
Reported-by: Casey Leedom <leedom@xxxxxxxxxxx>
Fixes: 4a336a23d619 ("kobject: copy env blob in one go")
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
lib/kobject_uevent.c | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)

Ok, I'm lost here, is this patch still needed for 4.15-final?

Yes this is needed, it solves the issue I reported.

And am I supposed to be taking it through my tree as the offending patch
didn't come from me? :)

Sorry for that, I sent a patch series (
8ca712c373a462cfa1b62272870b6c2c74aa83f9 )
that was mostly network related stuff (dealing with skbs and all rtnl batching),
and sent it to David before Dmitry patch was visible in David tree.

Yes, we believe fix in zap_modalias_env() is needed.