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Fri, 31 Jul 2026 08:11:54 +0000 (GMT) Received: from ala-exchng01.corp.ad.wrs.com (10.11.224.121) by ALA-EXCHNG02.corp.ad.wrs.com (10.11.224.122) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.61; Fri, 31 Jul 2026 01:11:53 -0700 Received: from pek-yzhou-d3.wrs.com (10.11.232.110) by ala-exchng01.corp.ad.wrs.com (10.11.224.121) with Microsoft SMTP Server id 15.1.2507.61 via Frontend Transport; Fri, 31 Jul 2026 01:11:52 -0700 From: Yun Zhou To: CC: , , Subject: [PATCH] usb: gadget: f_tcm: fix deadlock in usbg_make_tpg() Date: Fri, 31 Jul 2026 16:11:51 +0800 Message-ID: <20260731081151.285599-1-yun.zhou@windriver.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzMxMDA1OCBTYWx0ZWRfX+TBkDeyNUMSx z4CrVpi70KEC6b5ho01/i+fqGzwQJUHmRLoNlPcVM+IVd0VSYSResHpODSKa7KZyLvrvrt+6yIh kXLtinY3ff+T6DKdFpYTrOOSNqoRkTBForeEUzCLEUH6KiHp76jscqE8RmvfRJTPOCOeCZDznB0 0URDy9q5wyupEnH0ToJNcxbO6soT6jsYfNGU83Kh2EYEMcuViWVh6lnVTPSZMPU8OsFGDyJdSVh 4yDOnDg5gLXj0YL4WEluKxccmuV36mVVSiQixzpxh92xKwoKrGzXXkAVzlOfsKSV+kgT6B+917y L8Z7CpTTTAeZborPD8JHWxG/V8aXK4B5vI6ruVJHiq2vKHOlaE4/uvYw00lMG4PzAW3YkPikkV1 aP3zfj0rk6Xo444Z5sCoHdwzyZfcIb/TrJl8VOVgM1/4mSiUl/yNNnF78YEn8fq9GEcilXIZB/d 6oGUH2S/fwhg62ZHB9g== X-Proofpoint-GUID: v7ak1osDF2yFhIh_ZiIbEiU98Vs-G00p X-Proofpoint-ORIG-GUID: v7ak1osDF2yFhIh_ZiIbEiU98Vs-G00p X-Authority-Analysis: v=2.4 cv=W7sIkxWk c=1 sm=1 tr=0 ts=6a6c58ca cx=c_pps a=Lg6ja3A245NiLSnFpY5YKQ==:117 a=Lg6ja3A245NiLSnFpY5YKQ==:17 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=bi6dqmuHe4P4UrxVR6um:22 a=fTW__CHxibyLmBMfj2wP:22 a=edf1wS77AAAA:8 a=hSkVLCK3AAAA:8 a=VwQbUJbxAAAA:8 a=t7CeM3EgAAAA:8 a=jo3DrBat5IEn3YIh5xUA:9 a=DcSpbTIhAlouE1Uv7lRv:22 a=cQPPKAXgyycSBL8etih5:22 a=FdTzh2GWekK77mhwV6Dw:22 X-Proofpoint-Spam-Info: AW1haW4tMjYwNzMxMDA1OCBTYWx0ZWRfXwT18AIyaoSS6 02//rV++uPN8nA5x6swMH3ZKmUbPyzj3ojR5opibpuKyDUA9Bf2XcLez9Pc+CG5aHEaW4woS5sW LUeNRQ0Y1el2dfK2u1r6EDfRQTVidlV9rVVhybaHFlh8bIDrC6JJ X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-07-31_03,2026-07-30_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 phishscore=0 priorityscore=1501 lowpriorityscore=0 impostorscore=0 malwarescore=0 clxscore=1011 adultscore=0 suspectscore=0 bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607310058 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 --- drivers/usb/gadget/function/f_tcm.c | 23 ++++++++++++----------- 1 file changed, 12 insertions(+), 11 deletions(-) diff --git a/drivers/usb/gadget/function/f_tcm.c b/drivers/usb/gadget/function/f_tcm.c index b3fa5a17fd2d..c727c19db25d 100644 --- a/drivers/usb/gadget/function/f_tcm.c +++ b/drivers/usb/gadget/function/f_tcm.c @@ -1675,19 +1675,25 @@ static struct se_portal_group *usbg_make_tpg(struct se_wwn *wwn, 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_obj(struct usbg_tpg); @@ -1714,7 +1720,6 @@ static struct se_portal_group *usbg_make_tpg(struct se_wwn *wwn, 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; @@ -1727,8 +1732,6 @@ static struct se_portal_group *usbg_make_tpg(struct se_wwn *wwn, 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); @@ -2666,9 +2669,7 @@ static int tcm_set_name(struct usb_function_instance *f, const char *name) 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; } -- 2.43.0