This is a note to let you know that I've just added the patch titled rtnetlink: fix if_nlmsg_stats_size() under estimation to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: rtnetlink-fix-if_nlmsg_stats_size-under-estimation.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 8c12182633d5805d3bf9619804c556cc7f7fc534 Author: Eric Dumazet <edumazet@xxxxxxxxxx> Date: Tue Oct 5 14:04:17 2021 -0700 rtnetlink: fix if_nlmsg_stats_size() under estimation [ Upstream commit d34367991933d28bd7331f67a759be9a8c474014 ] rtnl_fill_statsinfo() is filling skb with one mandatory if_stats_msg structure. nlmsg_put(skb, pid, seq, type, sizeof(struct if_stats_msg), flags); But if_nlmsg_stats_size() never considered the needed storage. This bug did not show up because alloc_skb(X) allocates skb with extra tailroom, because of added alignments. This could very well be changed in the future to have deterministic behavior. Fixes: 10c9ead9f3c6 ("rtnetlink: add new RTM_GETSTATS message to dump link stats") Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx> Cc: Roopa Prabhu <roopa@xxxxxxxxxx> Acked-by: Roopa Prabhu <roopa@xxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index 911752e8a3e6..012143f313a8 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -3900,7 +3900,7 @@ nla_put_failure: static size_t if_nlmsg_stats_size(const struct net_device *dev, u32 filter_mask) { - size_t size = 0; + size_t size = NLMSG_ALIGN(sizeof(struct if_stats_msg)); if (stats_attr_valid(filter_mask, IFLA_STATS_LINK_64, 0)) size += nla_total_size_64bit(sizeof(struct rtnl_link_stats64));