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

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 <arnd@arndb.de>
Signed-off-by: default avatarLadi Prosek <lprosek@redhat.com>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
parent 9646b26e

drivers/virtio/virtio_balloon.c

+2 −0
Original line number Diff line number Diff line
@@ -254,12 +254,14 @@ static unsigned int 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,