From: Coly Li <col...@suse.de> commit cf83a17edeeb36195596d2dae060a7c381db35f1 upstream.
commit a10674bf2406 ("tcp: detecting the misuse of .sendpage for Slab objects") adds the checks for Slab pages, but the pages don't have page_count are still missing from the check. Network layer's sendpage method is not designed to send page_count 0 pages neither, therefore both PageSlab() and page_count() should be both checked for the sending page. This is exactly what sendpage_ok() does. This patch uses sendpage_ok() in do_tcp_sendpages() to detect misused .sendpage, to make the code more robust. Fixes: a10674bf2406 ("tcp: detecting the misuse of .sendpage for Slab objects") Suggested-by: Eric Dumazet <eric.duma...@gmail.com> Signed-off-by: Coly Li <col...@suse.de> Cc: Vasily Averin <v...@virtuozzo.com> Cc: David S. Miller <da...@davemloft.net> Cc: sta...@vger.kernel.org Signed-off-by: David S. Miller <da...@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> --- net/ipv4/tcp.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -970,7 +970,8 @@ ssize_t do_tcp_sendpages(struct sock *sk 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")) + WARN_ONCE(!sendpage_ok(page), + "page must not be a Slab one and have page_count > 0")) return -EINVAL; /* Wait for a connection to finish. One exception is TCP Fast Open