6.5-stable review patch. If anyone has any objections, please let me know.
------------------
From: Zhang Changzhong <zhangchangzhong@xxxxxxxxxx>
commit cc9b364bb1d58d3dae270c7a931a8cc717dc2b3b upstream.
There are race conditions that may lead to inet6_dev refcount underflow
in xfrm6_dst_destroy() and rt6_uncached_list_flush_dev().
One of the refcount underflow bugs is shown below:
(cpu 1) | (cpu 2)
xfrm6_dst_destroy() |
... |
in6_dev_put() |
| rt6_uncached_list_flush_dev()
... | ...
| in6_dev_put()
rt6_uncached_list_del() | ...
... |
xfrm6_dst_destroy() calls rt6_uncached_list_del() after in6_dev_put(),
so rt6_uncached_list_flush_dev() has a chance to call in6_dev_put()
again for the same inet6_dev.
Fix it by moving in6_dev_put() after rt6_uncached_list_del() in
xfrm6_dst_destroy().
Fixes: 510c321b5571 ("xfrm: reuse uncached_list to track xdsts")
Signed-off-by: Zhang Changzhong <zhangchangzhong@xxxxxxxxxx>
Reviewed-by: Xin Long <lucien.xin@xxxxxxxxx>
Signed-off-by: Steffen Klassert <steffen.klassert@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/ipv6/xfrm6_policy.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/net/ipv6/xfrm6_policy.c
+++ b/net/ipv6/xfrm6_policy.c
@@ -117,10 +117,10 @@ static void xfrm6_dst_destroy(struct dst
{
struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
- if (likely(xdst->u.rt6.rt6i_idev))
- in6_dev_put(xdst->u.rt6.rt6i_idev);
dst_destroy_metrics_generic(dst);
rt6_uncached_list_del(&xdst->u.rt6);
+ if (likely(xdst->u.rt6.rt6i_idev))
+ in6_dev_put(xdst->u.rt6.rt6i_idev);
xfrm_dst_destroy(xdst);
}
