5.4-stable review patch. If anyone has any objections, please let me know.
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From: Zhang Changzhong zhangchangzhong@huawei.com
[ Upstream commit cc9b364bb1d58d3dae270c7a931a8cc717dc2b3b ]
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@huawei.com Reviewed-by: Xin Long lucien.xin@gmail.com Signed-off-by: Steffen Klassert steffen.klassert@secunet.com Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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 @@ -120,11 +120,11 @@ 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); if (xdst->u.rt6.rt6i_uncached_list) 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); }