The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y git checkout FETCH_HEAD git cherry-pick -x cc9b364bb1d58d3dae270c7a931a8cc717dc2b3b # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2023102003-anagram-decency-29a0@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From cc9b364bb1d58d3dae270c7a931a8cc717dc2b3b Mon Sep 17 00:00:00 2001 From: Zhang Changzhong zhangchangzhong@huawei.com Date: Fri, 15 Sep 2023 19:20:41 +0800 Subject: [PATCH] xfrm6: fix inet6_dev refcount underflow problem

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

diff --git a/net/ipv6/xfrm6_policy.c b/net/ipv6/xfrm6_policy.c index 188224a76685..45d0f9a8b28c 100644 --- a/net/ipv6/xfrm6_policy.c +++ b/net/ipv6/xfrm6_policy.c @@ -117,10 +117,10 @@ static void xfrm6_dst_destroy(struct dst_entry *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); }