Commit f0bb2d50 authored by Arnd Bergmann's avatar Arnd Bergmann Committed by Michael S. Tsirkin

virtio_balloon: prevent uninitialized variable use

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: 9564e138 ("virtio: Add memory statistics reporting to the balloon driver (V4)")
Signed-off-by: default avatarArnd Bergmann <>
Signed-off-by: default avatarLadi Prosek <>
Signed-off-by: Michael S. Tsirkin's avatarMichael S. Tsirkin <>
parent 9646b26e
......@@ -254,12 +254,14 @@ static unsigned int update_balloon_stats(struct virtio_balloon *vb)
available = si_mem_available();
update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_IN,
update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_OUT,
update_stat(vb, idx++, VIRTIO_BALLOON_S_MAJFLT, events[PGMAJFAULT]);
update_stat(vb, idx++, VIRTIO_BALLOON_S_MINFLT, events[PGFAULT]);
update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMFREE,
update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMTOT,
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