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Tue, 18 Aug 2026 04:41:37 -0700 (PDT) X-Received: by 2002:a05:620a:4505:b0:92e:601b:8d43 with SMTP id af79cd13be357-936d22734femr2373142085a.1.1787053296955; Tue, 18 Aug 2026 04:41:36 -0700 (PDT) Received: from [192.168.120.193] ([178.235.128.140]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-6a3d8530d3bsm1811320a12.10.2026.08.18.04.41.33 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 18 Aug 2026 04:41:35 -0700 (PDT) Message-ID: <15b13316-a9b5-4577-9be1-98f4de17951d@oss.qualcomm.com> Date: Tue, 18 Aug 2026 13:41:33 +0200 Precedence: bulk X-Mailing-List: linux-i2c@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] i2c: qcom-cci: fix device_node refcount leak in cci_probe()/cci_remove() To: Liu Zhenlong , loic.poulain@oss.qualcomm.com, rfoss@kernel.org, andi.shyti@kernel.org Cc: vladimir.zapolskiy@linaro.org, wsa@kernel.org, andersson@kernel.org, linux-i2c@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org References: <20260815140931.53297-1-dragonliu2018@gmail.com> Content-Language: en-US From: Konrad Dybcio In-Reply-To: <20260815140931.53297-1-dragonliu2018@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Proofpoint-ORIG-GUID: xkIchZmwRDeZ3DWYrTeU1MqCW1mIoXVX X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODE4MDA4NSBTYWx0ZWRfX5eCnpxXXEf2j Oqnwgd0OmhIDKZB/kn25V2+fFryDe8MJw1JV+N/kTxPJqGpKC/9Dr4T91Ql2mur/aeau6cVhix4 ZJGT7TYnntrGsLqzbNK0kAAvSOl7vJgg0AuWSJZ0+ueIVFzBOqY/Ahqn1Km5Eg45O6MydHrtge9 KPLAE1Yrf0XTSz/xKL+947P8i1CQCcB7tSpOobl2kYtXkbhHsBk3zWuKSDtCTxtmqCKZHjZr3PK +Fx1FMpPiGMlRerkarzv+i2MDm+Rist8xBBzGgSryoEwTptWon9gb60LKiVbVQzMlXNt40fMjQA uhJFbxd+V1Nt/FgZOCxvtOukEP7f+svq6zr2LzlMRUFiAsPXRwxtiY52LcyiCT7PabFsWTbGTJP 9fpJGl+VfDe3X+oFKQDRn1GIXxoOSGWqsSNrchQmXURUOe+efLyu8CfMoxah63PYSlk0lTCJwT2 fQdu/PBV0RPw0dxLpTg== X-Authority-Analysis: v=2.4 cv=K/IS2SWI c=1 sm=1 tr=0 ts=6a8444f1 cx=c_pps a=hnmNkyzTK/kJ09Xio7VxxA==:117 a=PRfkaYvzSr8QmIIGAkY2Sg==:17 a=IkcTkHD0fZMA:10 a=Sv0fKeRqtYgA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=3WHJM1ZQz_JShphwDgj5:22 a=VwQbUJbxAAAA:8 a=pGLkceISAAAA:8 a=S-fymDIK2t4towvNsLcA:9 a=QEXdDO2ut3YA:10 a=PEH46H7Ffwr30OY-TuGO:22 X-Proofpoint-Spam-Info: AW1haW4tMjYwODE4MDA4NSBTYWx0ZWRfX2TQcRqR+qgvH cp4FD7e/fM5suJrCQfgqzT+wi59Hbt+cN/UA81KxrRyy+0PqZRSs1QjNRiVQJBwzL1ag7WAP1AP v4weeECYP+yWphfIG9D4oDensuisf+A= X-Proofpoint-GUID: xkIchZmwRDeZ3DWYrTeU1MqCW1mIoXVX X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-18_01,2026-08-12_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 suspectscore=0 clxscore=1015 impostorscore=0 lowpriorityscore=0 bulkscore=0 spamscore=0 priorityscore=1501 adultscore=0 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608180085 On 8/15/26 4:09 PM, Liu Zhenlong wrote: > cci_probe() calls of_node_get() to take an extra reference on the > child device_node when assigning it to the adapter device. The > matching of_node_put() calls exist in both the error cleanup path > and cci_remove(), but they are placed after i2c_del_adapter(). > > i2c_del_adapter() clears adap->dev with memset() at the end (commit > bd4bc3dbded9 ("i2c: Clear i2c_adapter.dev on adapter removal")), which > zeroes adap->dev.of_node before of_node_put() runs, turning it into a > no-op. The reference taken by of_node_get() is never released, leaking > the device_node on every cleanup of already-registered adapters and > every adapter removal. > > The commit that added of_node_get() and the matching of_node_put() > calls placed the puts after i2c_del_adapter(), so the bug has been > present since the fix was introduced. > > Cache the pointer before calling i2c_del_adapter(), the same approach > used in i2c-mux (i2c_mux_del_adapters) and mtd (commit 56570bdad5e3 > ("mtd: core: Fix refcount error in del_mtd_device()")). > > The of_node_put() in the i2c_add_adapter() failure path (before any > i2c_del_adapter() runs) is correct and left unchanged. > > Fixes: 02a4a69667a2 ("i2c: qcom-cci: don't put a device tree node before i2c_add_adapter()") > Cc: stable@vger.kernel.org > Assisted-by: Claude:claude-opus-5 > Signed-off-by: Liu Zhenlong > --- > drivers/i2c/busses/i2c-qcom-cci.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/drivers/i2c/busses/i2c-qcom-cci.c b/drivers/i2c/busses/i2c-qcom-cci.c > index bdeda3979c48..61c535b8196f 100644 > --- a/drivers/i2c/busses/i2c-qcom-cci.c > +++ b/drivers/i2c/busses/i2c-qcom-cci.c > @@ -618,8 +618,10 @@ static int cci_probe(struct platform_device *pdev) > > for (--i ; i >= 0; i--) { > if (cci->master[i].cci) { > + struct device_node *node = cci->master[i].adap.dev.of_node; > + > i2c_del_adapter(&cci->master[i].adap); > - of_node_put(cci->master[i].adap.dev.of_node); > + of_node_put(node); The fix seems correct, but the way it's done is still fragile - someone/a bot will surely come around in a couple weeks with a ""simplification"" undoing your change. Would a devm action here be a better choice? Konrad