Subject: linux-next: build warning after merge of the bpf-next tree

From: Stephen Rothwell <[email-masked]>
Date: Mon, 25 Mar 2019 09:28:04 +1100

Hi all,

After merging the bpf-next tree, today's linux-next build (x86_64
allmodconfig) produced this warning:

net/core/filter.c: In function 'bpf_skb_adjust_room':
net/core/filter.c:3022:31: warning: 'inner_trans' may be used uninitialized in this function [-Wmaybe-uninitialized]
   skb->inner_transport_header = inner_trans;
   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~
net/core/filter.c:2979:26: note: 'inner_trans' was declared here
  u16 mac_len, inner_net, inner_trans;
                          ^~~~~~~~~~~
net/core/filter.c:3021:29: warning: 'inner_net' may be used uninitialized in this function [-Wmaybe-uninitialized]
   skb->inner_network_header = inner_net;
   ~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~
net/core/filter.c:2979:15: note: 'inner_net' was declared here
  u16 mac_len, inner_net, inner_trans;
               ^~~~~~~~~
net/core/filter.c:3026:3: warning: 'mac_len' may be used uninitialized in this function [-Wmaybe-uninitialized]
   skb_set_network_header(skb, mac_len);
   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
net/core/filter.c:2979:6: note: 'mac_len' was declared here
  u16 mac_len, inner_net, inner_trans;
      ^~~~~~~

Introduced by commit

  868d523535c2 ("bpf: add bpf_skb_adjust_room encap flags")

This looks like a false positive, it seems that they are only set and
used when encap is true.

-- 
Cheers,
Stephen Rothwell