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[87.205.71.93]) by smtp.gmail.com with ESMTPSA id 187sm377199lfl.117.2020.11.20.07.16.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 20 Nov 2020 07:16:08 -0800 (PST) From: alardam@gmail.com X-Google-Original-From: marekx.majtyka@intel.com To: magnus.karlsson@intel.com, bjorn.topel@intel.com, ast@kernel.org, daniel@iogearbox.net, netdev@vger.kernel.org, jonathan.lemon@gmail.com Cc: Marek Majtyka , bpf@vger.kernel.org Subject: [PATCH bpf] xsk: fix incorrect netdev reference count Date: Fri, 20 Nov 2020 16:14:43 +0100 Message-Id: <20201120151443.105903-1-marekx.majtyka@intel.com> X-Mailer: git-send-email 2.27.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org From: Marek Majtyka Fix incorrect netdev reference count in xsk_bind operation. Incorrect reference count of the device appears when a user calls bind with the XDP_ZEROCOPY flag on an interface which does not support zero-copy. In such a case, an error is returned but the reference count is not decreased. This change fixes the fault, by decreasing the reference count in case of such an error. The problem being corrected appeared in '162c820ed896' for the first time, and the code was moved to new file location over the time with commit 'c2d3d6a47462'. This specific patch applies to all version starting from 'c2d3d6a47462'. The same solution should be applied but on different file (net/xdp/xdp_umem.c) and function (xdp_umem_assign_dev) for versions from '162c820ed896' to 'c2d3d6a47462' excluded. Fixes: 162c820ed896 ("xdp: hold device for umem regardless of zero- ...") Signed-off-by: Marek Majtyka --- net/xdp/xsk_buff_pool.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/net/xdp/xsk_buff_pool.c b/net/xdp/xsk_buff_pool.c index 8a3bf4e1318e..46d09bfb1923 100644 --- a/net/xdp/xsk_buff_pool.c +++ b/net/xdp/xsk_buff_pool.c @@ -185,8 +185,10 @@ static int __xp_assign_dev(struct xsk_buff_pool *pool, err_unreg_pool: if (!force_zc) err = 0; /* fallback to copy mode */ - if (err) + if (err) { xsk_clear_pool_at_qid(netdev, queue_id); + dev_put(netdev); + } return err; } -- 2.27.0