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([2a02:3035:b61:cd4c:428e:991d:75b:c0b0]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-49fbd32c5e1sm15131045e9.5.2026.09.16.11.15.21 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 16 Sep 2026 11:15:21 -0700 (PDT) Content-Type: multipart/mixed; boundary="------------XEnvVPO2Q6hJ7Mw5RBTj5USZ" Message-ID: <9e4b67a2-1975-43a6-b79f-00ad833c4214@suse.com> Date: Wed, 16 Sep 2026 20:15:20 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [BUG] usb: mdc800: possible circular locking dependency between io_lock and minor_rwsem To: CJ , gregkh@linuxfoundation.org, oneukum@suse.com, n7l8m4@u.northwestern.edu, kees@kernel.org Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org References: <5c30f641.6b79.1a09ed8b2bf.Coremail.firefly0158@163.com> Content-Language: en-US From: Oliver Neukum In-Reply-To: <5c30f641.6b79.1a09ed8b2bf.Coremail.firefly0158@163.com> This is a multi-part message in MIME format. --------------XEnvVPO2Q6hJ7Mw5RBTj5USZ Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 14.09.26 09:36, CJ wrote: > > Hi, > > > I am reporting a lockdep-detected circular locking dependency in the mdc800 USB > driver, triggered by a syzkaller USB reproducer. The issue is reproducible with > HEAD commit cee9395acd8043be0644b25c34bfa86623f2b935 (v7.3-rc1, Linux > 7.3.0-rc1). > > > The reproducer connects a synthetic USB device through dummy_hcd that enumerates > as the mdc800 camera, then opens the character device node. No filesystem or > image input is involved; the trigger is the connect-then-open sequence on a > device that binds to this driver. Hi, please try the attached patch. Regards Oliver --------------XEnvVPO2Q6hJ7Mw5RBTj5USZ Content-Type: text/x-patch; charset=UTF-8; name="0001-usb-misc-mdc800-avoid-circular-locking.patch" Content-Disposition: attachment; filename="0001-usb-misc-mdc800-avoid-circular-locking.patch" Content-Transfer-Encoding: base64 RnJvbSAwMWU0YTViN2YyMTViNWY2OWVjMWZkZGU4MjljMWNkMDk0OThhMjJmIE1vbiBTZXAg MTcgMDA6MDA6MDAgMjAwMQpGcm9tOiBPbGl2ZXIgTmV1a3VtIDxvbmV1a3VtQHN1c2UuY29t PgpEYXRlOiBXZWQsIDE2IFNlcCAyMDI2IDE3OjM3OjI1ICswMjAwClN1YmplY3Q6IFtQQVRD SF0gdXNiOiBtaXNjOiBtZGM4MDA6IGF2b2lkIGNpcmN1bGFyIGxvY2tpbmcKCk5vIG5lZWQg Zm9yIGxvY2tpbmcgaW4gcHJvYmUoKQoKU2lnbmVkLW9mZi1ieTogT2xpdmVyIE5ldWt1bSA8 b25ldWt1bUBzdXNlLmNvbT4KLS0tCiBkcml2ZXJzL3VzYi9pbWFnZS9tZGM4MDAuYyB8IDI2 ICsrKysrKysrKy0tLS0tLS0tLS0tLS0tLS0tCiAxIGZpbGUgY2hhbmdlZCwgOSBpbnNlcnRp b25zKCspLCAxNyBkZWxldGlvbnMoLSkKCmRpZmYgLS1naXQgYS9kcml2ZXJzL3VzYi9pbWFn ZS9tZGM4MDAuYyBiL2RyaXZlcnMvdXNiL2ltYWdlL21kYzgwMC5jCmluZGV4IGY3Y2FhMWM1 Y2JiNy4uOWVkZjBhZmU4ZGFkIDEwMDY0NAotLS0gYS9kcml2ZXJzL3VzYi9pbWFnZS9tZGM4 MDAuYworKysgYi9kcml2ZXJzL3VzYi9pbWFnZS9tZGM4MDAuYwpAQCAtNDgwLDE1ICs0ODAs NiBAQCBzdGF0aWMgaW50IG1kYzgwMF91c2JfcHJvYmUgKHN0cnVjdCB1c2JfaW50ZXJmYWNl ICppbnRmLAogCiAJZGV2X2luZm8oJmludGYtPmRldiwgIkZvdW5kIE11c3RlayBNREM4MDAg b24gVVNCLlxuIik7CiAKLQltdXRleF9sb2NrKCZtZGM4MDAtPmlvX2xvY2spOwotCi0JcmV0 dmFsID0gdXNiX3JlZ2lzdGVyX2RldihpbnRmLCAmbWRjODAwX2NsYXNzKTsKLQlpZiAocmV0 dmFsKSB7Ci0JCWRldl9lcnIoJmludGYtPmRldiwgIk5vdCBhYmxlIHRvIGdldCBhIG1pbm9y IGZvciB0aGlzIGRldmljZS5cbiIpOwotCQltdXRleF91bmxvY2soJm1kYzgwMC0+aW9fbG9j ayk7Ci0JCXJldHVybiAtRU5PREVWOwotCX0KLQogCW1kYzgwMC0+ZGV2PWRldjsKIAltZGM4 MDAtPm9wZW49MDsKIApAQCAtNTI2LDcgKzUxNywxMSBAQCBzdGF0aWMgaW50IG1kYzgwMF91 c2JfcHJvYmUgKHN0cnVjdCB1c2JfaW50ZXJmYWNlICppbnRmLAogCiAJbWRjODAwLT5zdGF0 ZT1SRUFEWTsKIAotCW11dGV4X3VubG9jaygmbWRjODAwLT5pb19sb2NrKTsKKwlyZXR2YWwg PSB1c2JfcmVnaXN0ZXJfZGV2KGludGYsICZtZGM4MDBfY2xhc3MpOworCWlmIChyZXR2YWwp IHsKKwkJZGV2X2VycigmaW50Zi0+ZGV2LCAiTm90IGFibGUgdG8gZ2V0IGEgbWlub3IgZm9y IHRoaXMgZGV2aWNlLlxuIik7CisJCXJldHVybiAtRU5PREVWOworCX0KIAkKIAl1c2Jfc2V0 X2ludGZkYXRhKGludGYsIG1kYzgwMCk7CiAJcmV0dXJuIDA7CkBAIC01NDgsMTUgKzU0Mywx MiBAQCBzdGF0aWMgdm9pZCBtZGM4MDBfdXNiX2Rpc2Nvbm5lY3QgKHN0cnVjdCB1c2JfaW50 ZXJmYWNlICppbnRmKQogCiAJCXVzYl9kZXJlZ2lzdGVyX2RldihpbnRmLCAmbWRjODAwX2Ns YXNzKTsKIAotCQkvKiBtdXN0IGJlIHVuZGVyIGxvY2sgdG8gbWFrZSBzdXJlIG5vIFVSQgot CQkgICBpcyBzdWJtaXR0ZWQgYWZ0ZXIgdXNiX2tpbGxfdXJiKCkgKi8KLQkJbXV0ZXhfbG9j aygmbWRjODAwLT5pb19sb2NrKTsKIAkJbWRjODAwLT5zdGF0ZT1OT1RfQ09OTkVDVEVEOwog Ci0JCXVzYl9raWxsX3VyYihtZGM4MDAtPmlycV91cmIpOwotCQl1c2Jfa2lsbF91cmIobWRj ODAwLT53cml0ZV91cmIpOwotCQl1c2Jfa2lsbF91cmIobWRjODAwLT5kb3dubG9hZF91cmIp OwotCQltdXRleF91bmxvY2soJm1kYzgwMC0+aW9fbG9jayk7CisJCXVzYl9wb2lzb25fdXJi KG1kYzgwMC0+aXJxX3VyYik7CisJCXVzYl9wb2lzb25fdXJiKG1kYzgwMC0+d3JpdGVfdXJi KTsKKwkJdXNiX3BvaXNvbl91cmIobWRjODAwLT5kb3dubG9hZF91cmIpOworCiAKIAkJbWRj ODAwLT5kZXYgPSBOVUxMOwogCQl1c2Jfc2V0X2ludGZkYXRhKGludGYsIE5VTEwpOwotLSAK Mi41NS4wCgo= --------------XEnvVPO2Q6hJ7Mw5RBTj5USZ--