From 15cac17d9d3906c098128e8ee3a9d8721991677a Mon Sep 17 00:00:00 2001 From: Coly Li Date: Fri, 2 Oct 2020 16:27:31 +0800 Subject: [PATCH] tcp: use sendpage_ok() to detect misused .sendpage 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 Signed-off-by: Coly Li Cc: Vasily Averin Cc: David S. Miller Cc: stable@vger.kernel.org Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv4/tcp.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 2ffa33b5ef40..97f2b11ce203 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -971,7 +971,8 @@ ssize_t do_tcp_sendpages(struct sock *sk, struct page *page, int offset, 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