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From: David Hildenbrand <david@redhat.com>
To: Arnd Bergmann <arnd@arndb.de>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Jason Wang <jasowang@redhat.com>
Cc: Yisheng Xie <xieyisheng1@huawei.com>,
	Konstantin Neumoin <kneumoin@virtuozzo.com>,
	linux-kernel@vger.kernel.org,
	virtualization@lists.linux-foundation.org,
	Minchan Kim <minchan@kernel.org>,
	"Denis V. Lunev" <den@openvz.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Ingo Molnar <mingo@kernel.org>, Ladi Prosek <lprosek@redhat.com>
Subject: Re: [PATCH] virtio_balloon: prevent uninitialized variable use
Date: Fri, 24 Mar 2017 19:38:46 +0100	[thread overview]
Message-ID: <de7e1bac-d5e9-a984-499f-6e7e0a48b78e@redhat.com> (raw)
In-Reply-To: <20170323151728.679684-1-arnd@arndb.de>

On 23.03.2017 16:17, Arnd Bergmann wrote:
> The latest gcc-7.0.1 snapshot reports a new warning:
> 
> virtio/virtio_balloon.c: In function 'update_balloon_stats':
> virtio/virtio_balloon.c:258:26: error: 'events[2]' is used uninitialized in this function [-Werror=uninitialized]
> virtio/virtio_balloon.c:260:26: error: 'events[3]' is used uninitialized in this function [-Werror=uninitialized]
> virtio/virtio_balloon.c:261:56: error: 'events[18]' is used uninitialized in this function [-Werror=uninitialized]
> virtio/virtio_balloon.c:262:56: error: 'events[17]' is used uninitialized in this function [-Werror=uninitialized]
> 
> This seems absolutely right, so we should add an extra check to
> prevent copying uninitialized stack data into the statistics.
> From all I can tell, this has been broken since the statistics code
> was originally added in 2.6.34.
> 
> Fixes: 9564e138b1f6 ("virtio: Add memory statistics reporting to the balloon driver (V4)")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>  drivers/virtio/virtio_balloon.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
> index 4e1191508228..cd5c54e2003d 100644
> --- a/drivers/virtio/virtio_balloon.c
> +++ b/drivers/virtio/virtio_balloon.c
> @@ -254,12 +254,14 @@ static void update_balloon_stats(struct virtio_balloon *vb)
>  
>  	available = si_mem_available();
>  
> +#ifdef CONFIG_VM_EVENT_COUNTERS
>  	update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_IN,
>  				pages_to_bytes(events[PSWPIN]));
>  	update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_OUT,
>  				pages_to_bytes(events[PSWPOUT]));
>  	update_stat(vb, idx++, VIRTIO_BALLOON_S_MAJFLT, events[PGMAJFAULT]);
>  	update_stat(vb, idx++, VIRTIO_BALLOON_S_MINFLT, events[PGFAULT]);
> +#endif
>  	update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMFREE,
>  				pages_to_bytes(i.freeram));
>  	update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMTOT,
> 

CC'ing Ladi

-- 

Thanks,

David

WARNING: multiple messages have this Message-ID (diff)
From: David Hildenbrand <david@redhat.com>
To: Arnd Bergmann <arnd@arndb.de>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Jason Wang <jasowang@redhat.com>
Cc: Yisheng Xie <xieyisheng1@huawei.com>,
	Konstantin Neumoin <kneumoin@virtuozzo.com>,
	linux-kernel@vger.kernel.org,
	virtualization@lists.linux-foundation.org,
	Minchan Kim <minchan@kernel.org>,
	"Denis V. Lunev" <den@openvz.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Ingo Molnar <mingo@kernel.org>
Subject: Re: [PATCH] virtio_balloon: prevent uninitialized variable use
Date: Fri, 24 Mar 2017 19:38:46 +0100	[thread overview]
Message-ID: <de7e1bac-d5e9-a984-499f-6e7e0a48b78e@redhat.com> (raw)
In-Reply-To: <20170323151728.679684-1-arnd@arndb.de>

On 23.03.2017 16:17, Arnd Bergmann wrote:
> The latest gcc-7.0.1 snapshot reports a new warning:
> 
> virtio/virtio_balloon.c: In function 'update_balloon_stats':
> virtio/virtio_balloon.c:258:26: error: 'events[2]' is used uninitialized in this function [-Werror=uninitialized]
> virtio/virtio_balloon.c:260:26: error: 'events[3]' is used uninitialized in this function [-Werror=uninitialized]
> virtio/virtio_balloon.c:261:56: error: 'events[18]' is used uninitialized in this function [-Werror=uninitialized]
> virtio/virtio_balloon.c:262:56: error: 'events[17]' is used uninitialized in this function [-Werror=uninitialized]
> 
> This seems absolutely right, so we should add an extra check to
> prevent copying uninitialized stack data into the statistics.
> From all I can tell, this has been broken since the statistics code
> was originally added in 2.6.34.
> 
> Fixes: 9564e138b1f6 ("virtio: Add memory statistics reporting to the balloon driver (V4)")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>  drivers/virtio/virtio_balloon.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
> index 4e1191508228..cd5c54e2003d 100644
> --- a/drivers/virtio/virtio_balloon.c
> +++ b/drivers/virtio/virtio_balloon.c
> @@ -254,12 +254,14 @@ static void update_balloon_stats(struct virtio_balloon *vb)
>  
>  	available = si_mem_available();
>  
> +#ifdef CONFIG_VM_EVENT_COUNTERS
>  	update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_IN,
>  				pages_to_bytes(events[PSWPIN]));
>  	update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_OUT,
>  				pages_to_bytes(events[PSWPOUT]));
>  	update_stat(vb, idx++, VIRTIO_BALLOON_S_MAJFLT, events[PGMAJFAULT]);
>  	update_stat(vb, idx++, VIRTIO_BALLOON_S_MINFLT, events[PGFAULT]);
> +#endif
>  	update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMFREE,
>  				pages_to_bytes(i.freeram));
>  	update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMTOT,
> 

CC'ing Ladi

-- 

Thanks,

David

  parent reply	other threads:[~2017-03-24 18:39 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-03-23 15:17 [PATCH] virtio_balloon: prevent uninitialized variable use Arnd Bergmann
2017-03-23 15:17 ` Arnd Bergmann
2017-03-23 15:31 ` Denis V. Lunev
2017-03-23 15:31   ` Denis V. Lunev
2017-03-24 18:38 ` David Hildenbrand [this message]
2017-03-24 18:38   ` David Hildenbrand
2017-03-24 20:11   ` Ladi Prosek
2017-03-24 20:11     ` Ladi Prosek
2017-03-24 20:40     ` Arnd Bergmann
2017-03-24 20:40       ` Arnd Bergmann
2017-03-24 20:59       ` Michael S. Tsirkin
2017-03-24 20:59         ` Michael S. Tsirkin
2017-03-27 10:02         ` Ladi Prosek
2017-03-27 10:02           ` Ladi Prosek
2017-03-28 16:18           ` Michael S. Tsirkin
2017-03-28 16:18             ` Michael S. Tsirkin
2017-03-28 16:48             ` Ladi Prosek
2017-03-28 16:48               ` Ladi Prosek

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