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 8195136167B; Sat, 12 Sep 2026 17:01:26 +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=1789232487; cv=none; b=Y6Kp9FOc/3cTPlWDNEMxC8mbqfc9nh0YlhtOopQnh0jMr6tSWePTqEPDA4njdA4v7UNEf3xJzukbBHr01eSPYFtjGKDWpctFIjEwajum/LY+G48Q8s8fT1erMnfRZOHjmZe0Pwg7uRMduVQvEFK6vsiydMN05QSxS/wQUZWqqDw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789232487; c=relaxed/simple; bh=nWKFMaldIyiIc1zEHd+EbvyBIpRuXso5ik9z1xLyVXU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=cg9q82TkYFbwG+iF0hUxIDAXK0Va+b90iNAwDB/hXSFmBLccTdtU3V7LJTuZoGqxawYjqReFh0WdBrEVHkhHs8YDDxrWyy6Vbgd5JVnPk+fFHuySZP2KpRETELwzupvJpuD4byj95PI6ybnY0WYzvrIwcoMUd6Nsa2OzkQ6UVT8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=gFAOdS/Y; 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="gFAOdS/Y" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2312E1F000FF; Sat, 12 Sep 2026 17:01:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789232486; bh=L2Q197iAVxhGfyaEpMmJQxuRbcOxcSv/oSWuvvkxqFE=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=gFAOdS/YqoBUEnh/xYdZEijrgSgJsAdy02YqBjtI3Oz23QjJfzgr68E/+vrPSjYe6 Kjh+iV9V4je7KHS5T+skOAwYfb7tTWkx8mb30o6/D82ELFv63yke8+8PcaMVM7bAvI qMYoxSYQrhfHfpQYvXTf6ZuzALVD98GyhsTUMgJ8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+c9f9d646b08f3b6032fe@syzkaller.appspotmail.com, Yun Zhou Subject: [PATCH 5.15 020/935] usb: gadget: f_tcm: fix deadlock in usbg_make_tpg() Date: Sat, 12 Sep 2026 08:50:50 +0200 Message-ID: <20260912065527.302148982@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260912065526.833703348@linuxfoundation.org> References: <20260912065526.833703348@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: Yun Zhou commit 9dbf74f4022f80f7669d2b3c22c5deb46c1b5674 upstream. usbg_make_tpg() held dep_lock while calling configfs_depend_item_unlocked(), which acquires the configfs root inode lock when operating across subsystems. This creates a circular lock dependency with configfs_rmdir(): dep_lock -> configfs root inode lock -> su_mutex -> dep_lock In usbg_make_tpg(), dep_lock only serialized the read of opts->ready, which is a monotonic flag that transitions from false to true exactly once (in tcm_set_name()) and never reverts. Remove dep_lock from usbg_make_tpg() entirely and use READ_ONCE/WRITE_ONCE to access opts->ready locklessly instead. Reported-by: syzbot+c9f9d646b08f3b6032fe@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=c9f9d646b08f3b6032fe Fixes: 4bb8548df632 ("usb: gadget: f_tcm: add configfs support") Cc: stable@vger.kernel.org Signed-off-by: Yun Zhou Link: https://patch.msgid.link/20260731081151.285599-1-yun.zhou@windriver.com Signed-off-by: Greg Kroah-Hartman --- drivers/usb/gadget/function/f_tcm.c | 23 ++++++++++++----------- 1 file changed, 12 insertions(+), 11 deletions(-) --- a/drivers/usb/gadget/function/f_tcm.c +++ b/drivers/usb/gadget/function/f_tcm.c @@ -1340,19 +1340,25 @@ static struct se_portal_group *usbg_make opts = container_of(tpg_instances[i].func_inst, struct f_tcm_opts, func_inst); - mutex_lock(&opts->dep_lock); - if (!opts->ready) - goto unlock_dep; + if (!READ_ONCE(opts->ready)) + goto unlock_inst; if (opts->has_dep) { if (!try_module_get(opts->dependent)) - goto unlock_dep; + goto unlock_inst; } else { + /* + * configfs_depend_item_unlocked() may acquire the configfs + * root inode lock when the target belongs to a different + * subsystem. Calling it under dep_lock would create a + * circular dependency: + * dep_lock -> configfs inode lock -> su_mutex -> dep_lock + */ ret = configfs_depend_item_unlocked( wwn->wwn_group.cg_subsys, &opts->func_inst.group.cg_item); if (ret) - goto unlock_dep; + goto unlock_inst; } tpg = kzalloc(sizeof(struct usbg_tpg), GFP_KERNEL); @@ -1378,7 +1384,6 @@ static struct se_portal_group *usbg_make tpg_instances[i].tpg = tpg; tpg->fi = tpg_instances[i].func_inst; - mutex_unlock(&opts->dep_lock); mutex_unlock(&tpg_instances_lock); return &tpg->se_tpg; @@ -1391,8 +1396,6 @@ unref_dep: module_put(opts->dependent); else configfs_undepend_item_unlocked(&opts->func_inst.group.cg_item); -unlock_dep: - mutex_unlock(&opts->dep_lock); unlock_inst: mutex_unlock(&tpg_instances_lock); @@ -2350,9 +2353,7 @@ static int tcm_set_name(struct usb_funct pr_debug("tcm: Activating %s\n", name); - mutex_lock(&opts->dep_lock); - opts->ready = true; - mutex_unlock(&opts->dep_lock); + WRITE_ONCE(opts->ready, true); return 0; }