[10/88] tcp: fix tcp_md5_hash_skb_data()

Steven Rostedt
2013-08-13T16:11:20Z

[-- Attachment #1: 0010-tcp-fix-tcp_md5_hash_skb_data.patch --]
[-- Type: text/plain, Size: 1645 bytes --]

3.6.11.7-rc1 stable review patch.
If anyone has any objections, please let me know.

------------------

From: Eric Dumazet <edumazet@google.com>

[ Upstream commit 54d27fcb338bd9c42d1dfc5a39e18f6f9d373c2e ]

TCP md5 communications fail [1] for some devices, because sg/crypto code
assume page offsets are below PAGE_SIZE.

This was discovered using mlx4 driver [2], but I suspect loopback
might trigger the same bug now we use order-3 pages in tcp_sendmsg()

[1] Failure is giving following messages.

huh, entered softirq 3 NET_RX ffffffff806ad230 preempt_count 00000100,
exited with 00000101?

[2] mlx4 driver uses order-2 pages to allocate RX frags

Reported-by: Matt Schnall <mischnal@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Bernhard Beck <bbeck@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
net/ipv4/tcp.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 094a01f..5871c25 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3368,8 +3368,11 @@ int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *hp,

for (i = 0; i < shi->nr_frags; ++i) {
const struct skb_frag_struct *f = &shi->frags[i];
- struct page *page = skb_frag_page(f);
- sg_set_page(&sg, page, skb_frag_size(f), f->page_offset);
+ unsigned int offset = f->page_offset;
+ struct page *page = skb_frag_page(f) + (offset >> PAGE_SHIFT);
+
+ sg_set_page(&sg, page, skb_frag_size(f),
+ offset_in_page(offset));
if (crypto_hash_update(desc, &sg, skb_frag_size(f)))
return 1;
}
--
1.7.10.4