BPF Archive on lore.kernel.org
 help / color / Atom feed
From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Magnus Karlsson <magnus.karlsson@intel.com>,
	Alexei Starovoitov <ast@kernel.org>,
	Sasha Levin <sashal@kernel.org>,
	netdev@vger.kernel.org, bpf@vger.kernel.org
Subject: [PATCH AUTOSEL 4.19 170/671] xsk: add missing smp_rmb() in xsk_mmap
Date: Thu, 16 Jan 2020 11:51:19 -0500
Message-ID: <20200116165940.10720-53-sashal@kernel.org> (raw)
In-Reply-To: <20200116165940.10720-1-sashal@kernel.org>

From: Magnus Karlsson <magnus.karlsson@intel.com>

[ Upstream commit e6762c8bcf982821935a2b1cb33cf8335d0eefae ]

All the setup code in AF_XDP is protected by a mutex with the
exception of the mmap code that cannot use it. To make sure that a
process banging on the mmap call at the same time as another process
is setting up the socket, smp_wmb() calls were added in the umem
registration code and the queue creation code, so that the published
structures that xsk_mmap needs would be consistent. However, the
corresponding smp_rmb() calls were not added to the xsk_mmap
code. This patch adds these calls.

Fixes: 37b076933a8e3 ("xsk: add missing write- and data-dependency barrier")
Fixes: c0c77d8fb787c ("xsk: add user memory registration support sockopt")
Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
 net/xdp/xsk.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index ff15207036dc..547fc4554b22 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -661,6 +661,8 @@ static int xsk_mmap(struct file *file, struct socket *sock,
 		if (!umem)
 			return -EINVAL;
+		/* Matches the smp_wmb() in XDP_UMEM_REG */
+		smp_rmb();
 		if (offset == XDP_UMEM_PGOFF_FILL_RING)
 			q = READ_ONCE(umem->fq);
 		else if (offset == XDP_UMEM_PGOFF_COMPLETION_RING)
@@ -670,6 +672,8 @@ static int xsk_mmap(struct file *file, struct socket *sock,
 	if (!q)
 		return -EINVAL;
+	/* Matches the smp_wmb() in xsk_init_queue */
+	smp_rmb();
 	qpg = virt_to_head_page(q->ring);
 	if (size > (PAGE_SIZE << compound_order(qpg)))
 		return -EINVAL;

           reply index

Thread overview: expand[flat|nested]  mbox.gz  Atom feed
 [parent not found: <20200116165940.10720-1-sashal@kernel.org>]

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200116165940.10720-53-sashal@kernel.org \
    --to=sashal@kernel.org \
    --cc=ast@kernel.org \
    --cc=bpf@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=magnus.karlsson@intel.com \
    --cc=netdev@vger.kernel.org \
    --cc=stable@vger.kernel.org \


* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

BPF Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/bpf/0 bpf/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 bpf bpf/ https://lore.kernel.org/bpf \
	public-inbox-index bpf

Example config snippet for mirrors

Newsgroup available over NNTP:

AGPL code for this site: git clone https://public-inbox.org/public-inbox.git