ip: silence udp zerocopy smatch false positive

extra_uref is used in __ip(6)_append_data only if uarg is set.

Smatch sees that the variable is passed to sock_zerocopy_put_abort.
This function accesses it only when uarg is set, but smatch cannot
infer this.

Make this dependency explicit.

Fixes: 52900d22288e ("udp: elide zerocopy operation in hot path")
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 1 deletions

diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 78f028bdad30..ab6618036afe 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -1130,7 +1130,8 @@ alloc_new_skb:
 error_efault:
         err = -EFAULT;
 error:
-        sock_zerocopy_put_abort(uarg, extra_uref);
+        if (uarg)
+                sock_zerocopy_put_abort(uarg, extra_uref);
         cork->length -= length;
         IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
         refcount_add(wmem_alloc_delta, &sk->sk_wmem_alloc);