rtnetlink: init handler refcounts to 1
authorFlorian Westphal <fw@strlen.de>
Thu, 10 Aug 2017 14:53:00 +0000 (16:53 +0200)
committerDavid S. Miller <davem@davemloft.net>
Thu, 10 Aug 2017 16:50:22 +0000 (09:50 -0700)
commitd38a65125f93b2fbd17cd37ccc5ec0f0b799cc55
treea9279b0bb53877dbf1ec2527d79a54311b58ccf8
parent8515ae38435895ba2862840d3e82140fc0a77554
rtnetlink: init handler refcounts to 1

If using CONFIG_REFCOUNT_FULL=y we get following splat:
 refcount_t: increment on 0; use-after-free.
WARNING: CPU: 0 PID: 304 at lib/refcount.c:152 refcount_inc+0x47/0x50
Call Trace:
 rtnetlink_rcv_msg+0x191/0x260
 ...

This warning is harmless (0 is "no callback running", not "memory
was freed").

Use '1' as the new 'no handler is running' base instead of 0 to avoid
this.

Fixes: 019a316992ee ("rtnetlink: add reference counting to prevent module unload while dump is in progress")
Reported-by: Sabrina Dubroca <sdubroca@redhat.com>
Reported-by: kernel test robot <fengguang.wu@intel.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/core/rtnetlink.c