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Tue, 13 Jan 2026 05:29:24 +0000 (GMT) From: Nilay Shroff To: linux-block@vger.kernel.org Cc: axboe@kernel.dk, gjoyce@ibm.com, Nilay Shroff , stable@vger.kernel.org Subject: [PATCH] null_blk: fix kmemleak by releasing references to fault configfs items Date: Tue, 13 Jan 2026 10:58:04 +0530 Message-ID: <20260113052901.1741689-1-nilay@linux.ibm.com> X-Mailer: git-send-email 2.52.0 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: kQUVrZhw2c5FNefoDXKU7aChJ3JL8nkQ X-Proofpoint-ORIG-GUID: kQUVrZhw2c5FNefoDXKU7aChJ3JL8nkQ X-Authority-Analysis: v=2.4 cv=TaibdBQh c=1 sm=1 tr=0 ts=6965d838 cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=vUbySO9Y5rIA:10 a=VkNPw1HP01LnGYTKEx00:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=w_JtO988ZX80fDk7qXcA:9 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMTEzMDA0MSBTYWx0ZWRfX1yO5nWOxgRLY VmnGqnIOBcqm8iLM0MIuivwP1xhGy2itnP8m8yYU29omP8gBOv5Brldesj4c2ZG10Pjqg/46cAY GLeFURfpNThy3FDSTG3QL79ci/Li5SsE9D6nT2N9OBTFv/hPmFFmi8mH7m8FtFDYyanmbclAI9d sOD2OV/yAye65fq7jjuxlsqqjG9+Uq2EB3du+th8jqPnazLJMEcQ92KKLFZmslcbJWMAX1AkOrW wrEgFM6PLh2eIsqMIZ0NNx56efoVLhh6v6NekLnKigeBXsjY0iRYWpWADaPdBiJKs6S3PJzi+wI 3ZAq5D27nU1/11ZX5TticQ9pwXbek/72cIfgbrCFsSK0UAa9IscxKpjkXnxW6pvnG7DBo7CYIU1 7usdFEL3PMINPaa4vNAQkvM3iYoyYuS6MU7h2nNeXeBd1NeyUI5jFZH6SxxRKaniSl0G9CrPUIQ bmu5IVkuXlsD9Pd8Y4A== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.9,FMLib:17.12.100.49 definitions=2026-01-12_07,2026-01-09_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 phishscore=0 impostorscore=0 bulkscore=0 clxscore=1015 suspectscore=0 priorityscore=1501 malwarescore=0 lowpriorityscore=0 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2512120000 definitions=main-2601130041 When CONFIG_BLK_DEV_NULL_BLK_FAULT_INJECTION is enabled, the null-blk driver sets up fault injection support by creating the timeout_inject, requeue_inject, and init_hctx_fault_inject configfs items as children of the top-level nullbX configfs group. However, when the nullbX device is removed, the references taken to these fault-config configfs items are not released. As a result, kmemleak reports a memory leak, for example: unreferenced object 0xc00000021ff25c40 (size 32): comm "mkdir", pid 10665, jiffies 4322121578 hex dump (first 32 bytes): 69 6e 69 74 5f 68 63 74 78 5f 66 61 75 6c 74 5f init_hctx_fault_ 69 6e 6a 65 63 74 00 88 00 00 00 00 00 00 00 00 inject.......... backtrace (crc 1a018c86): __kmalloc_node_track_caller_noprof+0x494/0xbd8 kvasprintf+0x74/0xf4 config_item_set_name+0xf0/0x104 config_group_init_type_name+0x48/0xfc fault_config_init+0x48/0xf0 0xc0080000180559e4 configfs_mkdir+0x304/0x814 vfs_mkdir+0x49c/0x604 do_mkdirat+0x314/0x3d0 sys_mkdir+0xa0/0xd8 system_call_exception+0x1b0/0x4f0 system_call_vectored_common+0x15c/0x2ec Fix this by explicitly releasing the references to the fault-config configfs items when dropping the reference to the top-level nullbX configfs group. Cc: stable@vger.kernel.org Fixes: bb4c19e030f4 ("block: null_blk: make fault-injection dynamically configurable per device") Signed-off-by: Nilay Shroff --- v1->v2: Added fixes and stable tags --- drivers/block/null_blk/main.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c index c7c0fb79a6bf..4c0632ab4e1b 100644 --- a/drivers/block/null_blk/main.c +++ b/drivers/block/null_blk/main.c @@ -665,12 +665,22 @@ static void nullb_add_fault_config(struct nullb_device *dev) configfs_add_default_group(&dev->init_hctx_fault_config.group, &dev->group); } +static void nullb_del_fault_config(struct nullb_device *dev) +{ + config_item_put(&dev->init_hctx_fault_config.group.cg_item); + config_item_put(&dev->requeue_config.group.cg_item); + config_item_put(&dev->timeout_config.group.cg_item); +} + #else static void nullb_add_fault_config(struct nullb_device *dev) { } +static void nullb_del_fault_config(struct nullb_device *dev) +{ +} #endif static struct @@ -702,7 +712,7 @@ nullb_group_drop_item(struct config_group *group, struct config_item *item) null_del_dev(dev->nullb); mutex_unlock(&lock); } - + nullb_del_fault_config(dev); config_item_put(item); } -- 2.52.0