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Mon, 26 Jan 2026 11:20:48 +0000 (GMT) Date: Mon, 26 Jan 2026 12:20:46 +0100 From: Vasily Gorbik To: Andrew Morton , Baoquan He , Coiby Xu Cc: Vivek Goyal , Dave Young , kexec@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH] crash_dump: fix dm_crypt keys locking and ref leak Message-ID: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Disposition: inline X-Patchwork-Bot: notify X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=Gr1PO01C c=1 sm=1 tr=0 ts=69774e13 cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=IkcTkHD0fZMA:10 a=vUbySO9Y5rIA:10 a=VkNPw1HP01LnGYTKEx00:22 a=VnNF1IyMAAAA:8 a=LJbtVcqbS3dIJv1iuH4A:9 a=QEXdDO2ut3YA:10 X-Proofpoint-GUID: murARjc-QDbNMnOReiZCiwmAmQv3Wde5 X-Proofpoint-ORIG-GUID: murARjc-QDbNMnOReiZCiwmAmQv3Wde5 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMTI2MDA5NiBTYWx0ZWRfX3ns8rBe4tE3g HRcsTtxM18CNftJ0Eh/DUncCLO20i9omltayiaXoj1OBpeDY6M9FLK1gEqgD45cEtlntcoz4MQv +EPMredhwbLKCqC3FGaRs9gNZIM/MfnGrOmaQ6l46mg2v5C8pnCmx5ix9kAMqeTlP6FcenIBZ7N nAw07VOrUqC0x+BqjSDTuW2gR7ZyoEv1KYXjyod7I/vXSadlKsRRsUbXWjHD/5Kt9OLQXRMJIJI iZBfHbfuqDiWzyr7nVIeqrr7ZADOgIsFVp1PV2oqbCVUGIf8z+RDsgVYcyQWxJtrBb0UCxcTcLI C1uBAj6fZKTRE0oW/QMj/J0py+RwSaF4OuLcg7bcusXd3kDZpPDqBK3r2mxA5U27bqd+rOxuIGM 1nV7uZHyBZugYxiGIpy3gi9EqwmDGuvh9dkbdW7vn7XPvSXD5Nh/wi8PkZzM928ygvYnUdsSDI9 5G35J11g2vhFbibHIhQ== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.20,FMLib:17.12.100.49 definitions=2026-01-26_02,2026-01-22_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 clxscore=1011 lowpriorityscore=0 suspectscore=0 impostorscore=0 phishscore=0 malwarescore=0 adultscore=0 spamscore=0 bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2601150000 definitions=main-2601260096 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" crash_load_dm_crypt_keys() reads dm-crypt volume keys from the user keyring. It uses user_key_payload_locked() without holding key->sem, which makes lockdep complain when kexec_file_load() assembles the crash image: =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D WARNING: suspicious RCU usage ----------------------------- ./include/keys/user-type.h:53 suspicious rcu_dereference_protected() usag= e! other info that might help us debug this: rcu_scheduler_active =3D 2, debug_locks =3D 1 no locks held by kexec/4875. stack backtrace: Call Trace: dump_stack_lvl+0x5d/0x80 lockdep_rcu_suspicious.cold+0x4e/0x96 crash_load_dm_crypt_keys+0x314/0x390 bzImage64_load+0x116/0x9a0 ? __lock_acquire+0x464/0x1ba0 __do_sys_kexec_file_load+0x26a/0x4f0 do_syscall_64+0xbd/0x430 entry_SYSCALL_64_after_hwframe+0x77/0x7f In addition, the key returned by request_key() is never key_put()'d, leaking a key reference on each load attempt. Take key->sem while copying the payload and drop the key reference afterwards. Fixes: 479e58549b0f ("crash_dump: store dm crypt keys in kdump reserved mem= ory") Signed-off-by: Vasily Gorbik --- kernel/crash_dump_dm_crypt.c | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) diff --git a/kernel/crash_dump_dm_crypt.c b/kernel/crash_dump_dm_crypt.c index 0d23dc1de67c..37129243054d 100644 --- a/kernel/crash_dump_dm_crypt.c +++ b/kernel/crash_dump_dm_crypt.c @@ -143,6 +143,7 @@ static int read_key_from_user_keying(struct dm_crypt_ke= y *dm_key) { const struct user_key_payload *ukp; struct key *key; + int ret =3D 0; =20 kexec_dprintk("Requesting logon key %s", dm_key->key_desc); key =3D request_key(&key_type_logon, dm_key->key_desc, NULL); @@ -152,20 +153,28 @@ static int read_key_from_user_keying(struct dm_crypt_= key *dm_key) return PTR_ERR(key); } =20 + down_read(&key->sem); ukp =3D user_key_payload_locked(key); - if (!ukp) - return -EKEYREVOKED; + if (!ukp) { + ret =3D -EKEYREVOKED; + goto out; + } =20 if (ukp->datalen > KEY_SIZE_MAX) { pr_err("Key size %u exceeds maximum (%u)\n", ukp->datalen, KEY_SIZE_MAX); - return -EINVAL; + ret =3D -EINVAL; + goto out; } =20 memcpy(dm_key->data, ukp->data, ukp->datalen); dm_key->key_size =3D ukp->datalen; kexec_dprintk("Get dm crypt key (size=3D%u) %s: %8ph\n", dm_key->key_size, dm_key->key_desc, dm_key->data); - return 0; + +out: + up_read(&key->sem); + key_put(key); + return ret; } =20 struct config_key { --=20 2.52.0