Re: [PATCH net] xfrm6: fix inet6_dev refcount underflow problem
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From: Steffen Klassert <steffen.klassert@secunet.com>
Date: 2023-09-25 05:42:39
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On Fri, Sep 15, 2023 at 07:20:41PM +0800, Zhang Changzhong wrote:
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 <redacted>Applied, thanks a lot!