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[2620:137:e000::1:20]) by mx.google.com with ESMTP id j15-20020aa7de8f000000b0045c0c18dde7si9527728edv.524.2022.10.17.19.28.36; Mon, 17 Oct 2022 19:29:00 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20210112 header.b=V5hcJVkr; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230120AbiJRCV6 (ORCPT + 99 others); Mon, 17 Oct 2022 22:21:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43542 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229520AbiJRCV5 (ORCPT ); Mon, 17 Oct 2022 22:21:57 -0400 Received: from mail-pl1-x62c.google.com (mail-pl1-x62c.google.com [IPv6:2607:f8b0:4864:20::62c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1F6FA8D0CB; Mon, 17 Oct 2022 19:21:48 -0700 (PDT) Received: by mail-pl1-x62c.google.com with SMTP id i6so12467917pli.12; Mon, 17 Oct 2022 19:21:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=xQe6WDAOYHq4a+xfdiJbwfTzKRbnd4s6fpLl3pLZwHY=; b=V5hcJVkrAsENglV9EVi00qDhW6ik0sjdL0tWfmnBI0IlkBwsWfWxJGPli2xhRJIGlI bPeBEdW27XAsJW+Y7cTSLwK/Y2mraw7s9Vq1Ewzup49cXCzeZDPIK+3Ztg+JJk5vB2kK 4JgB936N2XKc/fw4JFFh+zOj7Yx0syn2KQ7lq2waPuhywowqKjemRoiyH8u2/QyAsM1k dAA7zEeIAx4OQNTWMi0F8GsClmmNyJhE/UICuQoNXYBJdLxUHAsdVbAVBVtPgXzj8IBu Xozns9wxsChPOeO6y/NpZt0JcFCs537Veit/oXRK0Af2/BK59fJ5EMhVqmGYpxvIXQT0 3Bcw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=xQe6WDAOYHq4a+xfdiJbwfTzKRbnd4s6fpLl3pLZwHY=; b=a6ZOCNu60jsAw3fsFzQz3y9Y1x49kKiJJxjKMvRA+dWyH+rOxiD4dd+nWr9EUTlciw /6R4VWhI5boEF9dfF4mgLjH1ZSb42oKCzRRWssqGvpiD9JYDRx38K143I4indKk6G3xb bIj9EygKKTmTuoHfmMCG9Xx1VWLrt3fC+Z8guHfOmXXM4FiCaRB5C4PgcKRNr35kVukh yQsCplZIewPeLSfUX+yU89Q1UAso2w7m+lAvA7KjXFceeoQVeCP8gy7qHkkSVi2eTKvk STqkZUmZ5pJLGkUNhY3j7EUHJZqKZfyenbZRQiw8l6XYg2BwTWFJ8g9WAwBCMA70cl2Q LfZA== X-Gm-Message-State: ACrzQf1RGpSfkDUcVh2oCz2HE1Imojr6J/I1hdo6ick4r+3zYRrzdrUQ vuXzPa5Tpdy7wzpFqny1Abo= X-Received: by 2002:a17:90b:3b50:b0:20d:93f3:9c8d with SMTP id ot16-20020a17090b3b5000b0020d93f39c8dmr34106749pjb.150.1666059706442; Mon, 17 Oct 2022 19:21:46 -0700 (PDT) Received: from localhost ([159.226.94.113]) by smtp.gmail.com with ESMTPSA id w18-20020a170902e89200b0017c37a5a2fdsm7303815plg.216.2022.10.17.19.21.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 17 Oct 2022 19:21:45 -0700 (PDT) From: Hawkins Jiawei To: Marcel Holtmann , Johan Hedberg , Luiz Augusto von Dentz , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: 18801353760@163.com, linux-bluetooth@vger.kernel.org, linux-kernel@vger.kernel.org, luiz.von.dentz@intel.com, netdev@vger.kernel.org, syzbot+8f819e36e01022991cfa@syzkaller.appspotmail.com, syzkaller-bugs@googlegroups.com, yin31149@gmail.com Subject: [PATCH v2] Bluetooth: L2CAP: Fix memory leak in vhci_write Date: Tue, 18 Oct 2022 10:18:51 +0800 Message-Id: <20221018021851.2900-1-yin31149@gmail.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 X-Spam-Status: No, score=-1.8 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_ENVFROM_END_DIGIT, FREEMAIL_FROM,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1746920870163883337?= X-GMAIL-MSGID: =?utf-8?q?1746990677650042285?= Syzkaller reports a memory leak as follows: ==================================== BUG: memory leak unreferenced object 0xffff88810d81ac00 (size 240): [...] hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [] __alloc_skb+0x1f9/0x270 net/core/skbuff.c:418 [] alloc_skb include/linux/skbuff.h:1257 [inline] [] bt_skb_alloc include/net/bluetooth/bluetooth.h:469 [inline] [] vhci_get_user drivers/bluetooth/hci_vhci.c:391 [inline] [] vhci_write+0x5f/0x230 drivers/bluetooth/hci_vhci.c:511 [] call_write_iter include/linux/fs.h:2192 [inline] [] new_sync_write fs/read_write.c:491 [inline] [] vfs_write+0x42d/0x540 fs/read_write.c:578 [] ksys_write+0x9d/0x160 fs/read_write.c:631 [] do_syscall_x64 arch/x86/entry/common.c:50 [inline] [] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 [] entry_SYSCALL_64_after_hwframe+0x63/0xcd ==================================== HCI core will uses hci_rx_work() to process frame, which is queued to the hdev->rx_q tail in hci_recv_frame() by HCI driver. Yet the problem is that, HCI core may not free the skb after handling ACL data packets. To be more specific, when start fragment does not contain the L2CAP length, HCI core just copies skb into conn->rx_skb and finishes frame process in l2cap_recv_acldata(), without freeing the skb, which triggers the above memory leak. This patch solves it by releasing the relative skb, after processing the above case in l2cap_recv_acldata(). [Thanks Luiz Augusto von Dentz for his suggestion on using break] Fixes: 4d7ea8ee90e4 ("Bluetooth: L2CAP: Fix handling fragmented length") Link: https://lore.kernel.org/all/0000000000000d0b1905e6aaef64@google.com/ Reported-and-tested-by: syzbot+8f819e36e01022991cfa@syzkaller.appspotmail.com Signed-off-by: Hawkins Jiawei --- v2: - refactor the commit message on the problem description - refactor the goto drop with break, suggested by Luiz Augusto von Dentz v1: https://lore.kernel.org/all/20221017074432.12177-1-yin31149@gmail.com/ net/bluetooth/l2cap_core.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c index 1f34b82ca0ec..f0fb234c2e54 100644 --- a/net/bluetooth/l2cap_core.c +++ b/net/bluetooth/l2cap_core.c @@ -8426,9 +8426,8 @@ void l2cap_recv_acldata(struct hci_conn *hcon, struct sk_buff *skb, u16 flags) * expected length. */ if (skb->len < L2CAP_LEN_SIZE) { - if (l2cap_recv_frag(conn, skb, conn->mtu) < 0) - goto drop; - return; + l2cap_recv_frag(conn, skb, conn->mtu); + break; } len = get_unaligned_le16(skb->data) + L2CAP_HDR_SIZE; @@ -8472,7 +8471,7 @@ void l2cap_recv_acldata(struct hci_conn *hcon, struct sk_buff *skb, u16 flags) /* Header still could not be read just continue */ if (conn->rx_skb->len < L2CAP_LEN_SIZE) - return; + break; } if (skb->len > conn->rx_len) {