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From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Jesper Dangaard Brouer <brouer@redhat.com>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Sasha Levin <sashal@kernel.org>,
	netdev@vger.kernel.org, bpf@vger.kernel.org
Subject: [PATCH AUTOSEL 4.19 130/219] bpf/cpumap: make sure frame_size for build_skb is aligned if headroom isn't
Date: Fri, 22 Nov 2019 00:47:42 -0500	[thread overview]
Message-ID: <20191122054911.1750-123-sashal@kernel.org> (raw)
In-Reply-To: <20191122054911.1750-1-sashal@kernel.org>

From: Jesper Dangaard Brouer <brouer@redhat.com>

[ Upstream commit 77ea5f4cbe2084db9ab021ba73fb7eadf1610884 ]

The frame_size passed to build_skb must be aligned, else it is
possible that the embedded struct skb_shared_info gets unaligned.

For correctness make sure that xdpf->headroom in included in the
alignment. No upstream drivers can hit this, as all XDP drivers provide
an aligned headroom.  This was discovered when playing with implementing
XDP support for mvneta, which have a 2 bytes DSA header, and this
Marvell ARM64 platform didn't like doing atomic operations on an
unaligned skb_shinfo(skb)->dataref addresses.

Fixes: 1c601d829ab0 ("bpf: cpumap xdp_buff to skb conversion and allocation")
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 kernel/bpf/cpumap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/bpf/cpumap.c b/kernel/bpf/cpumap.c
index 24aac0d0f4127..8974b3755670e 100644
--- a/kernel/bpf/cpumap.c
+++ b/kernel/bpf/cpumap.c
@@ -183,7 +183,7 @@ static struct sk_buff *cpu_map_build_skb(struct bpf_cpu_map_entry *rcpu,
 	 * is not at a fixed memory location, with mixed length
 	 * packets, which is bad for cache-line hotness.
 	 */
-	frame_size = SKB_DATA_ALIGN(xdpf->len) + xdpf->headroom +
+	frame_size = SKB_DATA_ALIGN(xdpf->len + xdpf->headroom) +
 		SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
 
 	pkt_data_start = xdpf->data - xdpf->headroom;
-- 
2.20.1


       reply	other threads:[~2019-11-22  6:23 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20191122054911.1750-1-sashal@kernel.org>
2019-11-22  5:47 ` Sasha Levin [this message]
2019-11-22  5:48 ` [PATCH AUTOSEL 4.19 195/219] bpf: decrease usercnt if bpf_map_new_fd() fails in bpf_map_get_fd_by_id() Sasha Levin
2019-11-22  5:48 ` [PATCH AUTOSEL 4.19 199/219] bpf: drop refcount if bpf_map_new_fd() fails in map_create() Sasha Levin
2019-11-22  5:49 ` [PATCH AUTOSEL 4.19 218/219] xdp: fix cpumap redirect SKB creation bug Sasha Levin

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