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 B2C482D738A; Fri, 4 Sep 2026 06:06:39 +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=1788502000; cv=none; b=Ho2raLvJC0FpaA8iFfDHZF3Lt8bHvFaQXC3O6AICwTbAabYozQMwShyljUM1YKIvjxJ0ai9nnpOq07Yni48GoLDFonP2R4KXyeCWqbii7lSi8oQa+NSBrODm15W6jNCfImxOi3xQVAPHiIP5oN84kCLNq+IjSQIaLqiQKhQV0OY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788502000; c=relaxed/simple; bh=5pRtDXh5ZyRAHCVKJgnzZPdp1kb4sssrD4UCxWnMt14=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=IdEKQR2b37t3LbkwmnAVl9+XKNPtq4TwWN5+zE2N6d7ljQZEecFN0VO/g3tqWyw8cAhsdEwZypBUYSFCMrLkTr4bmRm8ZvDXu2hlbFEfzZYSYUwSkunuypmVwi5BZGdKUEfxMoSmLAane6nbViD86jALePvTlOj4qJH2od4k9Ko= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=AsF73UZY; 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="AsF73UZY" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 152F31F00A3D; Fri, 4 Sep 2026 06:06:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788501999; bh=0WtVJXbwQX/aI0lUAg8c6368NBi2WDFgJiL3gejavx8=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=AsF73UZYNPmZdOfUoGoaB7ehZQdKbvzAdwIthYwRHdvQ2A/pKv8Tjqrnb8AZZCyqR BDwDHIa96jEKlya1c7LTdZJA8PqHDVTOC1rKd1KV1FDhgEDcL5NffI1D3ImruOvyWq YgXTjYQKlSFgYZcutmbHkZSx6O4jQ7ZEt3I7hZcM= 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 6.12 055/403] usb: gadget: f_tcm: fix deadlock in usbg_make_tpg() Date: Fri, 4 Sep 2026 06:57:38 +0200 Message-ID: <20260904045736.079044011@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260904045734.806166532@linuxfoundation.org> References: <20260904045734.806166532@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 6.12-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 @@ -1330,19 +1330,25 @@ 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); @@ -1368,7 +1374,6 @@ 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; @@ -1381,8 +1386,6 @@ 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); @@ -2317,9 +2320,7 @@ 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; }