tcp: detecting the misuse of .sendpage for Slab objects

sendpage was not designed for processing of the Slab pages,
in some situations it can trigger BUG_ON on receiving side.

Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index ad07dd71063da09843ccfbd3e00d3f41567e1205..dbb08140cdc95916fefbc7fb1178aa4d249c91e9 100644 (file)
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -943,6 +943,10 @@ ssize_t do_tcp_sendpages(struct sock *sk, struct page *page, int offset,
        ssize_t copied;
        long timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
 
+       if (IS_ENABLED(CONFIG_DEBUG_VM) &&
+           WARN_ONCE(PageSlab(page), "page must not be a Slab one"))
+               return -EINVAL;
+
        /* Wait for a connection to finish. One exception is TCP Fast Open
         * (passive side) where data is allowed to be sent before a connection
         * is fully established.