From: Ilias Apalodimas <ilias.apalodimas@linaro.org>
To: netdev@vger.kernel.org
Cc: Ilias Apalodimas <ilias.apalodimas@linaro.org>,
Alexander Duyck <alexanderduyck@fb.com>,
"David S. Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
Alexander Lobakin <alobakin@pm.me>,
Jonathan Lemon <jonathan.lemon@gmail.com>,
Willem de Bruijn <willemb@google.com>,
Miaohe Lin <linmiaohe@huawei.com>,
Guillaume Nault <gnault@redhat.com>,
Cong Wang <cong.wang@bytedance.com>,
Jesper Dangaard Brouer <brouer@redhat.com>,
Matteo Croce <mcroce@microsoft.com>,
linux-kernel@vger.kernel.org
Subject: [PATCH 1/1 v2] skbuff: Fix a potential race while recycling page_pool packets
Date: Fri, 9 Jul 2021 09:29:39 +0300 [thread overview]
Message-ID: <20210709062943.101532-1-ilias.apalodimas@linaro.org> (raw)
As Alexander points out, when we are trying to recycle a cloned/expanded
SKB we might trigger a race. The recycling code relies on the
pp_recycle bit to trigger, which we carry over to cloned SKBs.
If that cloned SKB gets expanded or if we get references to the frags,
call skbb_release_data() and overwrite skb->head, we are creating separate
instances accessing the same page frags. Since the skb_release_data()
will first try to recycle the frags, there's a potential race between
the original and cloned SKB, since both will have the pp_recycle bit set.
Fix this by explicitly those SKBs not recyclable.
The atomic_sub_return effectively limits us to a single release case,
and when we are calling skb_release_data we are also releasing the
option to perform the recycling, or releasing the pages from the page pool.
Fixes: 6a5bcd84e886 ("page_pool: Allow drivers to hint on SKB recycling")
Reported-by: Alexander Duyck <alexanderduyck@fb.com>
Suggested-by: Alexander Duyck <alexanderduyck@fb.com>
Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
---
Changes since v1:
- Set the recycle bit to 0 during skb_release_data instead of the
individual fucntions triggering the issue, in order to catch all
cases
net/core/skbuff.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 12aabcda6db2..f91f09a824be 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -663,7 +663,7 @@ static void skb_release_data(struct sk_buff *skb)
if (skb->cloned &&
atomic_sub_return(skb->nohdr ? (1 << SKB_DATAREF_SHIFT) + 1 : 1,
&shinfo->dataref))
- return;
+ goto exit;
skb_zcopy_clear(skb, true);
@@ -674,6 +674,8 @@ static void skb_release_data(struct sk_buff *skb)
kfree_skb_list(shinfo->frag_list);
skb_free_head(skb);
+exit:
+ skb->pp_recycle = 0;
}
/*
--
2.32.0.rc0
next reply other threads:[~2021-07-09 6:29 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-09 6:29 Ilias Apalodimas [this message]
2021-07-09 14:34 ` [PATCH 1/1 v2] skbuff: Fix a potential race while recycling page_pool packets Alexander Duyck
2021-07-09 17:29 ` Ilias Apalodimas
2021-07-12 11:52 ` Jesper Dangaard Brouer
2021-07-15 4:00 ` Yunsheng Lin
2021-07-15 10:00 ` Ilias Apalodimas
2021-07-15 10:38 ` Ilias Apalodimas
2021-07-15 10:47 ` Yunsheng Lin
2021-07-15 12:37 ` Ilias Apalodimas
2021-07-15 14:25 ` Alexander Duyck
2021-07-15 14:45 ` Ilias Apalodimas
2021-07-15 14:57 ` Alexander Duyck
2021-07-15 15:02 ` Ilias Apalodimas
2021-07-16 2:30 ` Yunsheng Lin
2021-07-16 6:43 ` Ilias Apalodimas
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