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.dumazet@gmail.com Signed-off-by: Coly Li colyli@suse.de Cc: Vasily Averin vvs@virtuozzo.com Cc: David S. Miller davem@davemloft.net Cc: stable@vger.kernel.org --- 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 31f3b858db81..2135ee7c806d 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -970,7 +970,8 @@ 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