[ 046/143] tcp: fix tcp_md5_hash_skb_data()

Willy Tarreau
2014-05-12T01:43:24Z

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: Willy Tarreau <w@1wt.eu>
---
net/ipv4/tcp.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 6232462..fc18410 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2826,7 +2826,11 @@ 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];
- sg_set_page(&sg, f->page, f->size, f->page_offset);
+ unsigned int offset = f->page_offset;
+ struct page *page = f->page + (offset >> PAGE_SHIFT);
+
+ sg_set_page(&sg, page, f->size,
+ offset_in_page(offset));
if (crypto_hash_update(desc, &sg, f->size))
return 1;
}
--
1.7.12.2.21.g234cd45.dirty