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Thu, 29 Jan 2026 14:46:42 -0800 (PST) X-Relaying-Domain: purestorage.com Received: from dev-csander.dev.purestorage.com (dev-csander.dev.purestorage.com [10.112.29.101]) by c7-smtp-2023.dev.purestorage.com (Postfix) with ESMTP id BBF1A341C9D; Thu, 29 Jan 2026 15:46:41 -0700 (MST) Received: by dev-csander.dev.purestorage.com (Postfix, from userid 1557716354) id B0C4AE40971; Thu, 29 Jan 2026 15:46:41 -0700 (MST) From: Caleb Sander Mateos To: Ming Lei , Jens Axboe Cc: Govindarajulu Varadarajan , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, Caleb Sander Mateos Subject: [PATCH 3/4] ublk: use READ_ONCE() to read struct ublksrv_ctrl_cmd Date: Thu, 29 Jan 2026 15:46:16 -0700 Message-ID: <20260129224618.975401-4-csander@purestorage.com> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20260129224618.975401-1-csander@purestorage.com> References: <20260129224618.975401-1-csander@purestorage.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" struct ublksrv_ctrl_cmd is part of the io_uring_sqe, which may lie in userspace-mapped memory. It's racy to access its fields with normal loads, as userspace may write to them concurrently. Use READ_ONCE() for all the ublksrv_ctrl_cmd field accesses to avoid the race. Fixes: 87213b0d847c ("ublk: allow non-blocking ctrl cmds in IO_URING_F_NONB= LOCK issue") Signed-off-by: Caleb Sander Mateos --- drivers/block/ublk_drv.c | 77 +++++++++++++++++++--------------------- 1 file changed, 37 insertions(+), 40 deletions(-) diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c index 29c6942450c2..49510216832f 100644 --- a/drivers/block/ublk_drv.c +++ b/drivers/block/ublk_drv.c @@ -4188,15 +4188,13 @@ static struct ublk_device *ublk_get_device_from_id(= int idx) spin_unlock(&ublk_idr_lock); =20 return ub; } =20 -static int ublk_ctrl_start_dev(struct ublk_device *ub, - const struct ublksrv_ctrl_cmd *header) +static int ublk_ctrl_start_dev(struct ublk_device *ub, int ublksrv_pid) { const struct ublk_param_basic *p =3D &ub->params.basic; - int ublksrv_pid =3D (int)header->data[0]; struct queue_limits lim =3D { .logical_block_size =3D 1 << p->logical_bs_shift, .physical_block_size =3D 1 << p->physical_bs_shift, .io_min =3D 1 << p->io_min_shift, .io_opt =3D 1 << p->io_opt_shift, @@ -4346,15 +4344,14 @@ static int ublk_ctrl_start_dev(struct ublk_device *= ub, mutex_unlock(&ub->mutex); return ret; } =20 static int ublk_ctrl_get_queue_affinity(struct ublk_device *ub, - const struct ublksrv_ctrl_cmd *header, u64 addr, u16 len) + u64 queue, u64 addr, u16 len) { void __user *argp =3D (void __user *)addr; cpumask_var_t cpumask; - unsigned long queue; unsigned int retlen; unsigned int i; int ret; =20 if (len * BITS_PER_BYTE < nr_cpu_ids) @@ -4362,11 +4359,10 @@ static int ublk_ctrl_get_queue_affinity(struct ublk= _device *ub, if (len & (sizeof(unsigned long)-1)) return -EINVAL; if (!addr) return -EINVAL; =20 - queue =3D header->data[0]; if (queue >=3D ub->dev_info.nr_hw_queues) return -EINVAL; =20 if (!zalloc_cpumask_var(&cpumask, GFP_KERNEL)) return -ENOMEM; @@ -4396,23 +4392,22 @@ static inline void ublk_dump_dev_info(struct ublksr= v_ctrl_dev_info *info) info->dev_id, info->flags); pr_devel("\t nr_hw_queues %d queue_depth %d\n", info->nr_hw_queues, info->queue_depth); } =20 -static int ublk_ctrl_add_dev(const struct ublksrv_ctrl_cmd *header, - u64 addr, u16 len) +static int ublk_ctrl_add_dev(u32 dev_id, u16 qid, u64 addr, u16 len) { void __user *argp =3D (void __user *)addr; struct ublksrv_ctrl_dev_info info; struct ublk_device *ub; int ret =3D -EINVAL; =20 if (len < sizeof(info) || !addr) return -EINVAL; - if (header->queue_id !=3D (u16)-1) { + if (qid !=3D (u16)-1) { pr_warn("%s: queue_id is wrong %x\n", - __func__, header->queue_id); + __func__, qid); return -EINVAL; } =20 if (copy_from_user(&info, argp, sizeof(info))) return -EFAULT; @@ -4473,17 +4468,17 @@ static int ublk_ctrl_add_dev(const struct ublksrv_c= trl_cmd *header, return -EINVAL; =20 /* the created device is always owned by current user */ ublk_store_owner_uid_gid(&info.owner_uid, &info.owner_gid); =20 - if (header->dev_id !=3D info.dev_id) { + if (dev_id !=3D info.dev_id) { pr_warn("%s: dev id not match %u %u\n", - __func__, header->dev_id, info.dev_id); + __func__, dev_id, info.dev_id); return -EINVAL; } =20 - if (header->dev_id !=3D U32_MAX && header->dev_id >=3D UBLK_MAX_UBLKS) { + if (dev_id !=3D U32_MAX && dev_id >=3D UBLK_MAX_UBLKS) { pr_warn("%s: dev id is too large. Max supported is %d\n", __func__, UBLK_MAX_UBLKS - 1); return -EINVAL; } =20 @@ -4505,11 +4500,11 @@ static int ublk_ctrl_add_dev(const struct ublksrv_c= trl_cmd *header, mutex_init(&ub->mutex); spin_lock_init(&ub->lock); mutex_init(&ub->cancel_mutex); INIT_WORK(&ub->partition_scan_work, ublk_partition_scan_work); =20 - ret =3D ublk_alloc_dev_number(ub, header->dev_id); + ret =3D ublk_alloc_dev_number(ub, dev_id); if (ret < 0) goto out_free_ub; =20 memcpy(&ub->dev_info, &info, sizeof(info)); =20 @@ -4641,17 +4636,15 @@ static int ublk_ctrl_del_dev(struct ublk_device **p= _ub, bool wait) if (wait && wait_event_interruptible(ublk_idr_wq, ublk_idr_freed(idx))) return -EINTR; return 0; } =20 -static inline void ublk_ctrl_cmd_dump(struct io_uring_cmd *cmd) +static inline void ublk_ctrl_cmd_dump(u32 cmd_op, u32 dev_id, u16 qid, + u64 data, u64 addr, u16 len) { - const struct ublksrv_ctrl_cmd *header =3D io_uring_sqe_cmd(cmd->sqe); - pr_devel("%s: cmd_op %x, dev id %d qid %d data %llx buf %llx len %u\n", - __func__, cmd->cmd_op, header->dev_id, header->queue_id, - header->data[0], header->addr, header->len); + __func__, cmd_op, dev_id, qid, data, addr, len); } =20 static void ublk_ctrl_stop_dev(struct ublk_device *ub) { ublk_stop_dev(ub); @@ -4819,13 +4812,12 @@ static int ublk_ctrl_start_recovery(struct ublk_dev= ice *ub, mutex_unlock(&ub->mutex); return ret; } =20 static int ublk_ctrl_end_recovery(struct ublk_device *ub, - const struct ublksrv_ctrl_cmd *header) + const struct ublksrv_ctrl_cmd *header, int ublksrv_pid) { - int ublksrv_pid =3D (int)header->data[0]; int ret =3D -EINVAL; =20 pr_devel("%s: Waiting for all FETCH_REQs, dev id %d...\n", __func__, header->dev_id); =20 @@ -4869,14 +4861,13 @@ static int ublk_ctrl_get_features(u64 addr, u16 len) return -EFAULT; =20 return 0; } =20 -static void ublk_ctrl_set_size(struct ublk_device *ub, const struct ublksr= v_ctrl_cmd *header) +static void ublk_ctrl_set_size(struct ublk_device *ub, u64 new_size) { struct ublk_param_basic *p =3D &ub->params.basic; - u64 new_size =3D header->data[0]; =20 mutex_lock(&ub->mutex); p->dev_sectors =3D new_size; set_capacity_and_notify(ub->ub_disk, p->dev_sectors); mutex_unlock(&ub->mutex); @@ -4950,15 +4941,13 @@ static int ublk_wait_for_idle_io(struct ublk_device= *ub, ret =3D 0; =20 return ret; } =20 -static int ublk_ctrl_quiesce_dev(struct ublk_device *ub, - const struct ublksrv_ctrl_cmd *header) +static int ublk_ctrl_quiesce_dev(struct ublk_device *ub, u64 timeout_ms) { /* zero means wait forever */ - u64 timeout_ms =3D header->data[0]; struct gendisk *disk; int ret =3D -ENODEV; =20 if (!(ub->dev_info.flags & UBLK_F_QUIESCE)) return -EOPNOTSUPP; @@ -5032,10 +5021,11 @@ static int ublk_ctrl_uring_cmd_permission(struct ub= lk_device *ub, { const struct ublksrv_ctrl_cmd *header =3D io_uring_sqe_cmd(cmd->sqe); bool unprivileged =3D ub->dev_info.flags & UBLK_F_UNPRIVILEGED_DEV; void __user *argp =3D (void __user *)*addr; char *dev_path =3D NULL; + u16 dev_path_len; int ret =3D 0; int mask; =20 if (!unprivileged) { if (!capable(CAP_SYS_ADMIN)) @@ -5054,17 +5044,18 @@ static int ublk_ctrl_uring_cmd_permission(struct ub= lk_device *ub, * User has to provide the char device path for unprivileged ublk * * header->addr always points to the dev path buffer, and * header->dev_path_len records length of dev path buffer. */ - if (!header->dev_path_len || header->dev_path_len > PATH_MAX) + dev_path_len =3D READ_ONCE(header->dev_path_len); + if (!dev_path_len || dev_path_len > PATH_MAX) return -EINVAL; =20 - if (*len < header->dev_path_len) + if (*len < dev_path_len) return -EINVAL; =20 - dev_path =3D memdup_user_nul(argp, header->dev_path_len); + dev_path =3D memdup_user_nul(argp, dev_path_len); if (IS_ERR(dev_path)) return PTR_ERR(dev_path); =20 ret =3D -EINVAL; switch (_IOC_NR(cmd->cmd_op)) { @@ -5091,12 +5082,12 @@ static int ublk_ctrl_uring_cmd_permission(struct ub= lk_device *ub, goto exit; } =20 ret =3D ublk_char_dev_permission(ub, dev_path, mask); if (!ret) { - *len -=3D header->dev_path_len; - *addr +=3D header->dev_path_len; + *len -=3D dev_path_len; + *addr +=3D dev_path_len; } pr_devel("%s: dev id %d cmd_op %x uid %d gid %d path %s ret %d\n", __func__, ub->ub_number, cmd->cmd_op, ub->dev_info.owner_uid, ub->dev_info.owner_gid, dev_path, ret); @@ -5123,23 +5114,29 @@ static int ublk_ctrl_uring_cmd(struct io_uring_cmd = *cmd, { const struct ublksrv_ctrl_cmd *header =3D io_uring_sqe_cmd(cmd->sqe); struct ublk_device *ub =3D NULL; u32 cmd_op =3D cmd->cmd_op; int ret =3D -EINVAL; + u32 dev_id; + u16 qid; + u64 data; u64 addr; u16 len; =20 if (ublk_ctrl_uring_cmd_may_sleep(cmd_op) && issue_flags & IO_URING_F_NONBLOCK) return -EAGAIN; =20 if (!(issue_flags & IO_URING_F_SQE128)) return -EINVAL; =20 + dev_id =3D READ_ONCE(header->dev_id); + qid =3D READ_ONCE(header->queue_id); + data =3D READ_ONCE(header->data[0]); addr =3D READ_ONCE(header->addr); len =3D READ_ONCE(header->len); - ublk_ctrl_cmd_dump(cmd); + ublk_ctrl_cmd_dump(cmd_op, dev_id, qid, data, addr, len); =20 ret =3D ublk_check_cmd_op(cmd_op); if (ret) goto out; =20 @@ -5148,42 +5145,42 @@ static int ublk_ctrl_uring_cmd(struct io_uring_cmd = *cmd, goto out; } =20 if (_IOC_NR(cmd_op) !=3D UBLK_CMD_ADD_DEV) { ret =3D -ENODEV; - ub =3D ublk_get_device_from_id(header->dev_id); + ub =3D ublk_get_device_from_id(dev_id); if (!ub) goto out; =20 ret =3D ublk_ctrl_uring_cmd_permission(ub, cmd, &addr, &len); if (ret) goto put_dev; } =20 switch (_IOC_NR(cmd_op)) { case UBLK_CMD_START_DEV: - ret =3D ublk_ctrl_start_dev(ub, header); + ret =3D ublk_ctrl_start_dev(ub, data); break; case UBLK_CMD_STOP_DEV: ublk_ctrl_stop_dev(ub); ret =3D 0; break; case UBLK_CMD_GET_DEV_INFO: case UBLK_CMD_GET_DEV_INFO2: ret =3D ublk_ctrl_get_dev_info(ub, addr, len); break; case UBLK_CMD_ADD_DEV: - ret =3D ublk_ctrl_add_dev(header, addr, len); + ret =3D ublk_ctrl_add_dev(dev_id, qid, addr, len); break; case UBLK_CMD_DEL_DEV: ret =3D ublk_ctrl_del_dev(&ub, true); break; case UBLK_CMD_DEL_DEV_ASYNC: ret =3D ublk_ctrl_del_dev(&ub, false); break; case UBLK_CMD_GET_QUEUE_AFFINITY: - ret =3D ublk_ctrl_get_queue_affinity(ub, header, addr, len); + ret =3D ublk_ctrl_get_queue_affinity(ub, data, addr, len); break; case UBLK_CMD_GET_PARAMS: ret =3D ublk_ctrl_get_params(ub, addr, len); break; case UBLK_CMD_SET_PARAMS: @@ -5191,18 +5188,18 @@ static int ublk_ctrl_uring_cmd(struct io_uring_cmd = *cmd, break; case UBLK_CMD_START_USER_RECOVERY: ret =3D ublk_ctrl_start_recovery(ub, header); break; case UBLK_CMD_END_USER_RECOVERY: - ret =3D ublk_ctrl_end_recovery(ub, header); + ret =3D ublk_ctrl_end_recovery(ub, header, data); break; case UBLK_CMD_UPDATE_SIZE: - ublk_ctrl_set_size(ub, header); + ublk_ctrl_set_size(ub, data); ret =3D 0; break; case UBLK_CMD_QUIESCE_DEV: - ret =3D ublk_ctrl_quiesce_dev(ub, header); + ret =3D ublk_ctrl_quiesce_dev(ub, data); break; case UBLK_CMD_TRY_STOP_DEV: ret =3D ublk_ctrl_try_stop_dev(ub); break; default: @@ -5213,11 +5210,11 @@ static int ublk_ctrl_uring_cmd(struct io_uring_cmd = *cmd, put_dev: if (ub) ublk_put_device(ub); out: pr_devel("%s: cmd done ret %d cmd_op %x, dev id %d qid %d\n", - __func__, ret, cmd->cmd_op, header->dev_id, header->queue_id); + __func__, ret, cmd_op, dev_id, qid); return ret; } =20 static const struct file_operations ublk_ctl_fops =3D { .open =3D nonseekable_open, --=20 2.45.2