xsk_getsockopt() is copying uninitialized stack memory to userspace when
`extra_stats` is `false`. Fix it.

Fixes: 8aa5a33578e9 ("xsk: Add new statistics")
Suggested-by: Dan Carpenter <dan.carpen...@oracle.com>
Signed-off-by: Peilin Ye <yepeilin...@gmail.com>
---
Doing `= {};` is sufficient since currently `struct xdp_statistics` is
defined as follows:

struct xdp_statistics {
        __u64 rx_dropped;
        __u64 rx_invalid_descs;
        __u64 tx_invalid_descs;
        __u64 rx_ring_full;
        __u64 rx_fill_ring_empty_descs;
        __u64 tx_ring_empty_descs;
};

When being copied to the userspace, `stats` will not contain any
uninitialized "holes" between struct fields.

Changes in v2:
    - Remove the "Cc: sta...@vger.kernel.org" tag. (Suggested by Song Liu
      <songliubrav...@fb.com>)
    - Initialize `stats` by assignment instead of using memset().
      (Suggested by Song Liu <songliubrav...@fb.com>)

 net/xdp/xsk.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index 26e3bba8c204..b2b533eddebf 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -840,7 +840,7 @@ static int xsk_getsockopt(struct socket *sock, int level, 
int optname,
        switch (optname) {
        case XDP_STATISTICS:
        {
-               struct xdp_statistics stats;
+               struct xdp_statistics stats = {};
                bool extra_stats = true;
                size_t stats_size;
 
-- 
2.25.1

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