Messages in this thread Patch in this message | | | From | Arnd Bergmann <> | Subject | [4.4-stable 12/22] virtio_balloon: prevent uninitialized variable use | Date | Tue, 20 Feb 2018 12:54:59 +0100 |
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commit f0bb2d50dfcc519f06f901aac88502be6ff1df2c upstream.
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> Signed-off-by: Ladi Prosek <lprosek@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> [arnd: backported to 4.4] Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- drivers/virtio/virtio_balloon.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c index 01d15dca940e..26d0dff069f0 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -239,12 +239,15 @@ static void update_balloon_stats(struct virtio_balloon *vb) all_vm_events(events); si_meminfo(&i); + +#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, -- 2.9.0
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