From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8B3B34908D9; Mon, 31 Aug 2026 14:04:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788185089; cv=none; b=psKMPvOHeo3bD6c0bTZUKWJ7yxWjCTgN9kRcuf+vzUSm2ti58TNpvufP6v4ROhnG5iOVW+IxF+IB3cx/K7sXv+F3A2ilxdeXlg5E0FCJYGyxjXGS3Bj/QMuJ6txS++4cH/vqc+Q9RCqH3UJzzeH8imTvEdVfaIFgidugP1ao8Bg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788185089; c=relaxed/simple; bh=YCT+5mPkBsYLkexlXwyrBWRHSFn/hsfSKoZ0hRz5eKQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=E8H2fW8By5chB9nvGYWBtxQCtyiTWB4UhNrdEtLb/ZAwhjQfIebjaghF+SuPgCeHsC+N0yeBE3ihnx3R1JQ6X+e3lfxxN7nb4bs6CcZaO6gT9z0cFOLDTE5w4NMlE3dgeaFaZfyv5kP0kTtrNPfpzpNK50pFG5m6YLkR1CCkk68= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=s8Tl9iad; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="s8Tl9iad" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E51101F000E9; Mon, 31 Aug 2026 14:04:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788185087; bh=0erng9ZrCLKHQLKTJ9LYd2tWaIjaY40iCvyl1wNaCXA=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=s8Tl9iadPTNHzaVjW74muuWTQmFoyHCllbhgPEIyn/coCI6498Q55BCKpkhUhTF1e NzCK0ZUfTOETQqP4CHq1VRRDK5hXmBZW/hWraCbPS7BTRtxnnLg/z5k8o6M+it2CVR 3EZcs4qlcQubKNfC1wnvKcV2wtEzHzBKJcSrum80= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Shuangpeng Bai Subject: [PATCH 5.15 49/69] usb: gadget: f_tcm: keep port count until LUN teardown completes Date: Mon, 31 Aug 2026 15:35:22 +0200 Message-ID: <20260831133401.110722342@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260831133358.601894154@linuxfoundation.org> References: <20260831133358.601894154@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Shuangpeng Bai commit c39d0916da47d94909391876c9e5bd429ea7b1b9 upstream. tcm_usbg_drop_nexus() permits session removal once tpg_port_count reaches zero. However, usbg_port_unlink() currently decrements that count from the fabric_pre_unlink() callback, before core_dev_del_lun() waits for active se_lun references to drain. If removal of the last LUN races a nexus removal, the latter can observe a zero port count and call target_remove_session(). This frees sess_cmd_map while an in-flight struct usbg_cmd, including its work item, can still be accessed. Overlapping the last-LUN unlink with nexus removal reproduces this lifetime violation as a DEBUG_OBJECTS "free active" warning for usbg_cmd_work, followed by a target-core BUG/Oops. The generic target-core unlink path has no callback after core_dev_del_lun() completes. Add an optional fabric_post_unlink() callback and use it for the f_tcm port count. The count now remains nonzero until core_dev_del_lun() has finished draining active LUN references, preventing nexus removal from freeing the session during command completion. Fixes: c52661d60f63 ("usb-gadget: Initial merge of target module for UASP + BOT") Cc: stable@vger.kernel.org Signed-off-by: Shuangpeng Bai Link: https://patch.msgid.link/20260807060733.3186624-1-shuangpeng.kernel@gmail.com Signed-off-by: Greg Kroah-Hartman --- drivers/target/target_core_fabric_configfs.c | 8 ++++++++ drivers/usb/gadget/function/f_tcm.c | 2 +- include/target/target_core_fabric.h | 2 ++ 3 files changed, 11 insertions(+), 1 deletion(-) --- a/drivers/target/target_core_fabric_configfs.c +++ b/drivers/target/target_core_fabric_configfs.c @@ -689,6 +689,14 @@ static void target_fabric_port_unlink( } core_dev_del_lun(se_tpg, lun); + + if (tf->tf_ops->fabric_post_unlink) { + /* + * Allow fabrics to release state that must remain valid until + * core_dev_del_lun() has drained all active LUN references. + */ + tf->tf_ops->fabric_post_unlink(se_tpg, lun); + } } static void target_fabric_port_release(struct config_item *item) --- a/drivers/usb/gadget/function/f_tcm.c +++ b/drivers/usb/gadget/function/f_tcm.c @@ -1714,7 +1714,7 @@ static const struct target_core_fabric_o .fabric_make_tpg = usbg_make_tpg, .fabric_drop_tpg = usbg_drop_tpg, .fabric_post_link = usbg_port_link, - .fabric_pre_unlink = usbg_port_unlink, + .fabric_post_unlink = usbg_port_unlink, .fabric_init_nodeacl = usbg_init_nodeacl, .tfc_wwn_attrs = usbg_wwn_attrs, --- a/include/target/target_core_fabric.h +++ b/include/target/target_core_fabric.h @@ -94,6 +94,8 @@ struct target_core_fabric_ops { struct se_lun *); void (*fabric_pre_unlink)(struct se_portal_group *, struct se_lun *); + void (*fabric_post_unlink)(struct se_portal_group *se_tpg, + struct se_lun *lun); struct se_tpg_np *(*fabric_make_np)(struct se_portal_group *, struct config_group *, const char *); void (*fabric_drop_np)(struct se_tpg_np *);