Re: [PATCH] virtio_balloon: prevent uninitialized variable use
From: Denis V. Lunev <hidden>
Date: 2017-03-23 15:32:05
Also in:
lkml
On 03/23/2017 06:17 PM, 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>Reviewed-by: Denis V. Lunev <redacted>
quoted hunk ↗ jump to hunk
--- 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,