From: Vasily Averin <vvs@virtuozzo.com>
To: Eric Dumazet <edumazet@google.com>, netdev@vger.kernel.org
Subject: [PATCH] tcp: detect use sendpage for slab-based objects
Date: Thu, 21 Feb 2019 18:30:17 +0300 [thread overview]
Message-ID: <a8655149-80b9-c75d-6528-0b851ea85de8@virtuozzo.com> (raw)
There was few incidents when XFS over network block device generates
IO requests with slab-based metadata. If these requests are processed
via sendpage path tcp_sendpage() calls skb_can_coalesce() and merges
neighbour slab objects into one skb fragment.
If receiving side is located on the same host tcp_recvmsg() can trigger
following BUG_ON
usercopy: kernel memory exposure attempt detected
from XXXXXX (kmalloc-512) (1024 bytes)
This patch helps to detect the reason of similar incidents on sending side.
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
---
net/ipv4/tcp.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 2079145a3b7c..cf9572f4fc0f 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -996,6 +996,7 @@ ssize_t do_tcp_sendpages(struct sock *sk, struct page *page, int offset,
goto wait_for_memory;
if (can_coalesce) {
+ WARN_ON_ONCE(PageSlab(page));
skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
} else {
get_page(page);
--
2.17.1
next reply other threads:[~2019-02-21 15:30 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-21 15:30 Vasily Averin [this message]
2019-02-21 16:00 ` [PATCH] tcp: detect use sendpage for slab-based objects Eric Dumazet
2019-02-22 14:02 ` Vasily Averin
2019-02-22 16:39 ` Eric Dumazet
2019-02-25 9:15 ` Vasily Averin
2019-02-25 9:32 ` Vasily Averin
2019-03-04 12:58 ` Vasily Averin
2019-03-04 15:51 ` Eric Dumazet
2019-03-05 14:24 ` Vasily Averin
[not found] ` <CANn89iKss+mzwbeZgy3Bzct6sBe3UeyezXXGocAYtOe9pP8a9w@mail.gmail.com>
2019-03-05 15:11 ` Eric Dumazet
2019-03-05 16:44 ` Eric Dumazet
2019-03-05 18:35 ` Vasily Averin
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