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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 81EF6340603; Thu, 29 Jan 2026 15:46:42 -0700 (MST) Received: by dev-csander.dev.purestorage.com (Postfix, from userid 1557716354) id 77E28E40456; 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 2/4] ublk: don't write to struct ublksrv_ctrl_cmd Date: Thu, 29 Jan 2026 15:46:15 -0700 Message-ID: <20260129224618.975401-3-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" ublk_ctrl_uring_cmd_permission() writes to struct ublksrv_ctrl_cmd's addr and len fields, which is racy because ublksrv_ctrl_cmd is part of the io_uring_sqe, which may lie in userspace-mapped memory. Store the values of addr in len in local variables instead 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 Reviewed-by: Ming Lei --- drivers/block/ublk_drv.c | 84 ++++++++++++++++++++-------------------- 1 file changed, 43 insertions(+), 41 deletions(-) diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c index 72ee83ae303d..29c6942450c2 100644 --- a/drivers/block/ublk_drv.c +++ b/drivers/block/ublk_drv.c @@ -4346,24 +4346,24 @@ 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) + const struct ublksrv_ctrl_cmd *header, u64 addr, u16 len) { - void __user *argp =3D (void __user *)(unsigned long)header->addr; + void __user *argp =3D (void __user *)addr; cpumask_var_t cpumask; unsigned long queue; unsigned int retlen; unsigned int i; int ret; =20 - if (header->len * BITS_PER_BYTE < nr_cpu_ids) + if (len * BITS_PER_BYTE < nr_cpu_ids) return -EINVAL; - if (header->len & (sizeof(unsigned long)-1)) + if (len & (sizeof(unsigned long)-1)) return -EINVAL; - if (!header->addr) + if (!addr) return -EINVAL; =20 queue =3D header->data[0]; if (queue >=3D ub->dev_info.nr_hw_queues) return -EINVAL; @@ -4375,15 +4375,15 @@ static int ublk_ctrl_get_queue_affinity(struct ublk= _device *ub, if (ub->tag_set.map[HCTX_TYPE_DEFAULT].mq_map[i] =3D=3D queue) cpumask_set_cpu(i, cpumask); } =20 ret =3D -EFAULT; - retlen =3D min_t(unsigned short, header->len, cpumask_size()); + retlen =3D min_t(unsigned short, len, cpumask_size()); if (copy_to_user(argp, cpumask, retlen)) goto out_free_cpumask; - if (retlen !=3D header->len && - clear_user(argp + retlen, header->len - retlen)) + if (retlen !=3D len && + clear_user(argp + retlen, len - retlen)) goto out_free_cpumask; =20 ret =3D 0; out_free_cpumask: free_cpumask_var(cpumask); @@ -4396,18 +4396,19 @@ 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) +static int ublk_ctrl_add_dev(const struct ublksrv_ctrl_cmd *header, + u64 addr, u16 len) { - void __user *argp =3D (void __user *)(unsigned long)header->addr; + void __user *argp =3D (void __user *)addr; struct ublksrv_ctrl_dev_info info; struct ublk_device *ub; int ret =3D -EINVAL; =20 - if (header->len < sizeof(info) || !header->addr) + if (len < sizeof(info) || !addr) return -EINVAL; if (header->queue_id !=3D (u16)-1) { pr_warn("%s: queue_id is wrong %x\n", __func__, header->queue_id); return -EINVAL; @@ -4682,16 +4683,15 @@ static int ublk_ctrl_try_stop_dev(struct ublk_devic= e *ub) out: ublk_put_disk(disk); return ret; } =20 -static int ublk_ctrl_get_dev_info(struct ublk_device *ub, - const struct ublksrv_ctrl_cmd *header) +static int ublk_ctrl_get_dev_info(struct ublk_device *ub, u64 addr, u16 le= n) { - void __user *argp =3D (void __user *)(unsigned long)header->addr; + void __user *argp =3D (void __user *)addr; =20 - if (header->len < sizeof(struct ublksrv_ctrl_dev_info) || !header->addr) + if (len < sizeof(struct ublksrv_ctrl_dev_info) || !addr) return -EINVAL; =20 if (copy_to_user(argp, &ub->dev_info, sizeof(ub->dev_info))) return -EFAULT; =20 @@ -4712,24 +4712,23 @@ static void ublk_ctrl_fill_params_devt(struct ublk_= device *ub) ub->params.devt.disk_minor =3D 0; } ub->params.types |=3D UBLK_PARAM_TYPE_DEVT; } =20 -static int ublk_ctrl_get_params(struct ublk_device *ub, - const struct ublksrv_ctrl_cmd *header) +static int ublk_ctrl_get_params(struct ublk_device *ub, u64 addr, u16 len) { - void __user *argp =3D (void __user *)(unsigned long)header->addr; + void __user *argp =3D (void __user *)addr; struct ublk_params_header ph; int ret; =20 - if (header->len <=3D sizeof(ph) || !header->addr) + if (len <=3D sizeof(ph) || !addr) return -EINVAL; =20 if (copy_from_user(&ph, argp, sizeof(ph))) return -EFAULT; =20 - if (ph.len > header->len || !ph.len) + if (ph.len > len || !ph.len) return -EINVAL; =20 if (ph.len > sizeof(struct ublk_params)) ph.len =3D sizeof(struct ublk_params); =20 @@ -4742,24 +4741,23 @@ static int ublk_ctrl_get_params(struct ublk_device = *ub, mutex_unlock(&ub->mutex); =20 return ret; } =20 -static int ublk_ctrl_set_params(struct ublk_device *ub, - const struct ublksrv_ctrl_cmd *header) +static int ublk_ctrl_set_params(struct ublk_device *ub, u64 addr, u16 len) { - void __user *argp =3D (void __user *)(unsigned long)header->addr; + void __user *argp =3D (void __user *)addr; struct ublk_params_header ph; int ret =3D -EFAULT; =20 - if (header->len <=3D sizeof(ph) || !header->addr) + if (len <=3D sizeof(ph) || !addr) return -EINVAL; =20 if (copy_from_user(&ph, argp, sizeof(ph))) return -EFAULT; =20 - if (ph.len > header->len || !ph.len || !ph.types) + if (ph.len > len || !ph.len || !ph.types) return -EINVAL; =20 if (ph.len > sizeof(struct ublk_params)) ph.len =3D sizeof(struct ublk_params); =20 @@ -4857,16 +4855,16 @@ static int ublk_ctrl_end_recovery(struct ublk_devic= e *ub, out_unlock: mutex_unlock(&ub->mutex); return ret; } =20 -static int ublk_ctrl_get_features(const struct ublksrv_ctrl_cmd *header) +static int ublk_ctrl_get_features(u64 addr, u16 len) { - void __user *argp =3D (void __user *)(unsigned long)header->addr; + void __user *argp =3D (void __user *)addr; u64 features =3D UBLK_F_ALL; =20 - if (header->len !=3D UBLK_FEATURES_LEN || !header->addr) + if (len !=3D UBLK_FEATURES_LEN || !addr) return -EINVAL; =20 if (copy_to_user(argp, &features, UBLK_FEATURES_LEN)) return -EFAULT; =20 @@ -5028,15 +5026,15 @@ static int ublk_char_dev_permission(struct ublk_dev= ice *ub, path_put(&path); return err; } =20 static int ublk_ctrl_uring_cmd_permission(struct ublk_device *ub, - struct io_uring_cmd *cmd) + struct io_uring_cmd *cmd, u64 *addr, u16 *len) { - struct ublksrv_ctrl_cmd *header =3D (struct ublksrv_ctrl_cmd *)io_uring_s= qe_cmd(cmd->sqe); + 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 *)(unsigned long)header->addr; + void __user *argp =3D (void __user *)*addr; char *dev_path =3D NULL; int ret =3D 0; int mask; =20 if (!unprivileged) { @@ -5059,11 +5057,11 @@ static int ublk_ctrl_uring_cmd_permission(struct ub= lk_device *ub, * header->dev_path_len records length of dev path buffer. */ if (!header->dev_path_len || header->dev_path_len > PATH_MAX) return -EINVAL; =20 - if (header->len < header->dev_path_len) + if (*len < header->dev_path_len) return -EINVAL; =20 dev_path =3D memdup_user_nul(argp, header->dev_path_len); if (IS_ERR(dev_path)) return PTR_ERR(dev_path); @@ -5093,12 +5091,12 @@ 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) { - header->len -=3D header->dev_path_len; - header->addr +=3D header->dev_path_len; + *len -=3D header->dev_path_len; + *addr +=3D header->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); @@ -5125,36 +5123,40 @@ 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; + 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 + addr =3D READ_ONCE(header->addr); + len =3D READ_ONCE(header->len); ublk_ctrl_cmd_dump(cmd); =20 ret =3D ublk_check_cmd_op(cmd_op); if (ret) goto out; =20 if (cmd_op =3D=3D UBLK_U_CMD_GET_FEATURES) { - ret =3D ublk_ctrl_get_features(header); + ret =3D ublk_ctrl_get_features(addr, len); 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); if (!ub) goto out; =20 - ret =3D ublk_ctrl_uring_cmd_permission(ub, cmd); + ret =3D ublk_ctrl_uring_cmd_permission(ub, cmd, &addr, &len); if (ret) goto put_dev; } =20 switch (_IOC_NR(cmd_op)) { @@ -5165,29 +5167,29 @@ static int ublk_ctrl_uring_cmd(struct io_uring_cmd = *cmd, 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, header); + ret =3D ublk_ctrl_get_dev_info(ub, addr, len); break; case UBLK_CMD_ADD_DEV: - ret =3D ublk_ctrl_add_dev(header); + ret =3D ublk_ctrl_add_dev(header, 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); + ret =3D ublk_ctrl_get_queue_affinity(ub, header, addr, len); break; case UBLK_CMD_GET_PARAMS: - ret =3D ublk_ctrl_get_params(ub, header); + ret =3D ublk_ctrl_get_params(ub, addr, len); break; case UBLK_CMD_SET_PARAMS: - ret =3D ublk_ctrl_set_params(ub, header); + ret =3D ublk_ctrl_set_params(ub, addr, len); break; case UBLK_CMD_START_USER_RECOVERY: ret =3D ublk_ctrl_start_recovery(ub, header); break; case UBLK_CMD_END_USER_RECOVERY: --=20 2.45.2