[PATCH net] tcp: fix crashes in do_tcp_sendpages()
From: Eric Dumazet <hidden>
Date: 2012-12-01 23:07:08
Subsystem:
networking [general], networking [tcp], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Neal Cardwell, Linus Torvalds
From: Eric Dumazet <edumazet@google.com> Recent network changes allowed high order pages being used for skb fragments. This uncovered a bug in do_tcp_sendpages() which was assuming its caller provided an array of order-0 page pointers. We only have to deal with a single page in this function, and its order is irrelevant. Reported-by: Willy Tarreau <w@1wt.eu> Tested-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Eric Dumazet <edumazet@google.com> --- net/ipv4/tcp.c | 15 ++++++--------- 1 file changed, 6 insertions(+), 9 deletions(-)
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 083092e..e457c7a 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c@@ -830,8 +830,8 @@ static int tcp_send_mss(struct sock *sk, int *size_goal, int flags) return mss_now; } -static ssize_t do_tcp_sendpages(struct sock *sk, struct page **pages, int poffset, - size_t psize, int flags) +static ssize_t do_tcp_sendpages(struct sock *sk, struct page *page, int offset, + size_t size, int flags) { struct tcp_sock *tp = tcp_sk(sk); int mss_now, size_goal;
@@ -858,12 +858,9 @@ static ssize_t do_tcp_sendpages(struct sock *sk, struct page **pages, int poffse if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN)) goto out_err; - while (psize > 0) { + while (size > 0) { struct sk_buff *skb = tcp_write_queue_tail(sk); - struct page *page = pages[poffset / PAGE_SIZE]; int copy, i; - int offset = poffset % PAGE_SIZE; - int size = min_t(size_t, psize, PAGE_SIZE - offset); bool can_coalesce; if (!tcp_send_head(sk) || (copy = size_goal - skb->len) <= 0) {
@@ -912,8 +909,8 @@ new_segment: TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_PSH; copied += copy; - poffset += copy; - if (!(psize -= copy)) + offset += copy; + if (!(size -= copy)) goto out; if (skb->len < size_goal || (flags & MSG_OOB))
@@ -960,7 +957,7 @@ int tcp_sendpage(struct sock *sk, struct page *page, int offset, flags); lock_sock(sk); - res = do_tcp_sendpages(sk, &page, offset, size, flags); + res = do_tcp_sendpages(sk, page, offset, size, flags); release_sock(sk); return res; }