x86/kprobes: Fix crash when probing CS CALL instructionsgrafted

When using eBPF to probe CS CALL instructions within a function,
a crash can be triggered.

The eBPF tool probes offset 257 of the __hrtimer_run_queues()
function:

<__hrtimer_run_queues+249>:  nopl   0x0(%rax,%rax,1)
<__hrtimer_run_queues+254>:  mov    %r14,%rdi
<__hrtimer_run_queues+257>:  cs call <__x86_indirect_thunk_r12>
<__hrtimer_run_queues+263>:  mov    %eax,%r12d
<__hrtimer_run_queues+266>:  xchg   %ax,%ax
<__hrtimer_run_queues+268>:  mov    %r13,%rdi

Which triggers this crash:

  BUG: unable to handle page fault for address: 00000000000f41c9
  #PF: supervisor write access in kernel mode
  #PF: error_code(0x0002) - not-present page
  PGD 0 P4D 0
  Oops: 0002 [#1] SMP NOPTI
  CPU: 1 PID: 0 Comm: swapper/1 Kdump: loaded Tainted: P
  RIP: 0010:__hrtimer_run_queues+0x106/0x230

Note that __hrtimer_run_queues+0x106 is __hrtimer_run_queues+262, which is
at the 6th byte of the above CS CALL instruction. Since the CS CALL
instruction occupies 6 bytes, the exception occurred in the middle of that
call instruction.

The root cause is that when using eBPF tools to probe in the middle of a
function, a kprobe with INT3 is used as the underlying implementation.

During single-step emulation of the original CALL instruction,
int3_emulate_call() assumes that the probed CALL instruction is 5 bytes
long. However, the actual CS-prefixed CALL instruction occupies 6 bytes,
so it constructs an incorrect exception return address. When the CPU
returns from the kprobe handler, the next instruction to be executed is at
the address of the last byte of that CS CALL instruction. Coincidentally,
starting from that address, the CPU fetches and decodes a completely
different instruction, which ultimately triggers a kernel crash.

Fix the issue by using the actual instruction length obtained from
the instruction decoder when constructing the exception return
address, rather than relying on the hardcoded CALL_INSN_SIZE macro.

[ mingo: Refined the changelog ]

Fixes: 6256e668b7af ("x86/kprobes: Use int3 instead of debug trap for single-step")
Suggested-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Jinke Han <jinkehan@didiglobal.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://patch.msgid.link/20260908073742.GA10517@didi-ThinkCentre-M920t-N000

1 files changed, 430 insertions, 0 deletions

diff --git a/drivers/nvme/target/fabrics-cmd.c b/drivers/nvme/target/fabrics-cmd.c
new file mode 100644
index 000000000..42d1d1811
--- /dev/null
+++ b/drivers/nvme/target/fabrics-cmd.c
@@ -0,0 +1,430 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * NVMe Fabrics command implementation.
+ * Copyright (c) 2015-2016 HGST, a Western Digital Company.
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+#include <linux/blkdev.h>
+#include "nvmet.h"
+
+static void nvmet_execute_prop_set(struct nvmet_req *req)
+{
+	u64 val = le64_to_cpu(req->cmd->prop_set.value);
+	u16 status = 0;
+
+	if (!nvmet_check_transfer_len(req, 0))
+		return;
+
+	if (req->cmd->prop_set.attrib & 1) {
+		req->error_loc =
+			offsetof(struct nvmf_property_set_command, attrib);
+		status = NVME_SC_INVALID_FIELD | NVME_STATUS_DNR;
+		goto out;
+	}
+
+	switch (le32_to_cpu(req->cmd->prop_set.offset)) {
+	case NVME_REG_CC:
+		nvmet_update_cc(req->sq->ctrl, val);
+		break;
+	default:
+		req->error_loc =
+			offsetof(struct nvmf_property_set_command, offset);
+		status = NVME_SC_INVALID_FIELD | NVME_STATUS_DNR;
+	}
+out:
+	nvmet_req_complete(req, status);
+}
+
+static void nvmet_execute_prop_get(struct nvmet_req *req)
+{
+	struct nvmet_ctrl *ctrl = req->sq->ctrl;
+	u16 status = 0;
+	u64 val = 0;
+
+	if (!nvmet_check_transfer_len(req, 0))
+		return;
+
+	if (req->cmd->prop_get.attrib & 1) {
+		switch (le32_to_cpu(req->cmd->prop_get.offset)) {
+		case NVME_REG_CAP:
+			val = ctrl->cap;
+			break;
+		default:
+			status = NVME_SC_INVALID_FIELD | NVME_STATUS_DNR;
+			break;
+		}
+	} else {
+		switch (le32_to_cpu(req->cmd->prop_get.offset)) {
+		case NVME_REG_VS:
+			val = ctrl->subsys->ver;
+			break;
+		case NVME_REG_CC:
+			val = ctrl->cc;
+			break;
+		case NVME_REG_CSTS:
+			val = ctrl->csts;
+			break;
+		case NVME_REG_CRTO:
+			val = NVME_CAP_TIMEOUT(ctrl->csts);
+			break;
+		default:
+			status = NVME_SC_INVALID_FIELD | NVME_STATUS_DNR;
+			break;
+		}
+	}
+
+	if (status && req->cmd->prop_get.attrib & 1) {
+		req->error_loc =
+			offsetof(struct nvmf_property_get_command, offset);
+	} else {
+		req->error_loc =
+			offsetof(struct nvmf_property_get_command, attrib);
+	}
+
+	req->cqe->result.u64 = cpu_to_le64(val);
+	nvmet_req_complete(req, status);
+}
+
+u32 nvmet_fabrics_admin_cmd_data_len(struct nvmet_req *req)
+{
+	struct nvme_command *cmd = req->cmd;
+
+	switch (cmd->fabrics.fctype) {
+#ifdef CONFIG_NVME_TARGET_AUTH
+	case nvme_fabrics_type_auth_send:
+		return nvmet_auth_send_data_len(req);
+	case nvme_fabrics_type_auth_receive:
+		return nvmet_auth_receive_data_len(req);
+#endif
+	default:
+		return 0;
+	}
+}
+
+u16 nvmet_parse_fabrics_admin_cmd(struct nvmet_req *req)
+{
+	struct nvme_command *cmd = req->cmd;
+
+	switch (cmd->fabrics.fctype) {
+	case nvme_fabrics_type_property_set:
+		req->execute = nvmet_execute_prop_set;
+		break;
+	case nvme_fabrics_type_property_get:
+		req->execute = nvmet_execute_prop_get;
+		break;
+#ifdef CONFIG_NVME_TARGET_AUTH
+	case nvme_fabrics_type_auth_send:
+		req->execute = nvmet_execute_auth_send;
+		break;
+	case nvme_fabrics_type_auth_receive:
+		req->execute = nvmet_execute_auth_receive;
+		break;
+#endif
+	default:
+		pr_debug("received unknown capsule type 0x%x\n",
+			cmd->fabrics.fctype);
+		req->error_loc = offsetof(struct nvmf_common_command, fctype);
+		return NVME_SC_INVALID_OPCODE | NVME_STATUS_DNR;
+	}
+
+	return 0;
+}
+
+u32 nvmet_fabrics_io_cmd_data_len(struct nvmet_req *req)
+{
+	struct nvme_command *cmd = req->cmd;
+
+	switch (cmd->fabrics.fctype) {
+#ifdef CONFIG_NVME_TARGET_AUTH
+	case nvme_fabrics_type_auth_send:
+		return nvmet_auth_send_data_len(req);
+	case nvme_fabrics_type_auth_receive:
+		return nvmet_auth_receive_data_len(req);
+#endif
+	default:
+		return 0;
+	}
+}
+
+u16 nvmet_parse_fabrics_io_cmd(struct nvmet_req *req)
+{
+	struct nvme_command *cmd = req->cmd;
+
+	switch (cmd->fabrics.fctype) {
+#ifdef CONFIG_NVME_TARGET_AUTH
+	case nvme_fabrics_type_auth_send:
+		req->execute = nvmet_execute_auth_send;
+		break;
+	case nvme_fabrics_type_auth_receive:
+		req->execute = nvmet_execute_auth_receive;
+		break;
+#endif
+	default:
+		pr_debug("received unknown capsule type 0x%x\n",
+			cmd->fabrics.fctype);
+		req->error_loc = offsetof(struct nvmf_common_command, fctype);
+		return NVME_SC_INVALID_OPCODE | NVME_STATUS_DNR;
+	}
+
+	return 0;
+}
+
+static u16 nvmet_install_queue(struct nvmet_ctrl *ctrl, struct nvmet_req *req)
+{
+	struct nvmf_connect_command *c = &req->cmd->connect;
+	u16 qid = le16_to_cpu(c->qid);
+	u16 sqsize = le16_to_cpu(c->sqsize);
+	struct nvmet_ctrl *old;
+	u16 mqes = NVME_CAP_MQES(ctrl->cap);
+	u16 ret;
+
+	if (!sqsize) {
+		pr_warn("queue size zero!\n");
+		req->error_loc = offsetof(struct nvmf_connect_command, sqsize);
+		req->cqe->result.u32 = IPO_IATTR_CONNECT_SQE(sqsize);
+		ret = NVME_SC_CONNECT_INVALID_PARAM | NVME_STATUS_DNR;
+		goto err;
+	}
+
+	if (ctrl->sqs[qid] != NULL) {
+		pr_warn("qid %u has already been created\n", qid);
+		req->error_loc = offsetof(struct nvmf_connect_command, qid);
+		return NVME_SC_CMD_SEQ_ERROR | NVME_STATUS_DNR;
+	}
+
+	/* for fabrics, this value applies to only the I/O Submission Queues */
+	if (qid && sqsize > mqes) {
+		pr_warn("sqsize %u is larger than MQES supported %u cntlid %d\n",
+				sqsize, mqes, ctrl->cntlid);
+		req->error_loc = offsetof(struct nvmf_connect_command, sqsize);
+		req->cqe->result.u32 = IPO_IATTR_CONNECT_SQE(sqsize);
+		return NVME_SC_CONNECT_INVALID_PARAM | NVME_STATUS_DNR;
+	}
+
+	old = cmpxchg(&req->sq->ctrl, NULL, ctrl);
+	if (old) {
+		pr_warn("queue already connected!\n");
+		req->error_loc = offsetof(struct nvmf_connect_command, opcode);
+		return NVME_SC_CONNECT_CTRL_BUSY | NVME_STATUS_DNR;
+	}
+
+	kref_get(&ctrl->ref);
+	old = cmpxchg(&req->cq->ctrl, NULL, ctrl);
+	if (old) {
+		pr_warn("queue already connected!\n");
+		req->error_loc = offsetof(struct nvmf_connect_command, opcode);
+		return NVME_SC_CONNECT_CTRL_BUSY | NVME_STATUS_DNR;
+	}
+
+	/* note: convert queue size from 0's-based value to 1's-based value */
+	nvmet_cq_setup(ctrl, req->cq, qid, sqsize + 1);
+	nvmet_sq_setup(ctrl, req->sq, qid, sqsize + 1);
+
+	if (c->cattr & NVME_CONNECT_DISABLE_SQFLOW) {
+		req->sq->sqhd_disabled = true;
+		req->cqe->sq_head = cpu_to_le16(0xffff);
+	}
+
+	if (ctrl->ops->install_queue) {
+		ret = ctrl->ops->install_queue(req->sq);
+		if (ret) {
+			pr_err("failed to install queue %d cntlid %d ret %x\n",
+				qid, ctrl->cntlid, ret);
+			ctrl->sqs[qid] = NULL;
+			goto err;
+		}
+	}
+
+	return 0;
+
+err:
+	req->sq->ctrl = NULL;
+	return ret;
+}
+
+static u32 nvmet_connect_result(struct nvmet_ctrl *ctrl, struct nvmet_sq *sq)
+{
+	bool needs_auth = nvmet_has_auth(ctrl, sq);
+	key_serial_t keyid = nvmet_queue_tls_keyid(sq);
+
+	/* Do not authenticate I/O queues */
+	if (sq->qid)
+		needs_auth = false;
+
+	if (keyid)
+		pr_debug("%s: ctrl %d qid %d should %sauthenticate, tls psk %08x\n",
+			 __func__, ctrl->cntlid, sq->qid,
+			 needs_auth ? "" : "not ", keyid);
+	else
+		pr_debug("%s: ctrl %d qid %d should %sauthenticate%s\n",
+			 __func__, ctrl->cntlid, sq->qid,
+			 needs_auth ? "" : "not ",
+			 ctrl->concat ? ", secure concatenation" : "");
+	return (u32)ctrl->cntlid |
+		(needs_auth ? NVME_CONNECT_AUTHREQ_ATR : 0);
+}
+
+static void nvmet_execute_admin_connect(struct nvmet_req *req)
+{
+	struct nvmf_connect_command *c = &req->cmd->connect;
+	struct nvmf_connect_data *d;
+	struct nvmet_ctrl *ctrl = NULL;
+	struct nvmet_alloc_ctrl_args args = {
+		.port = req->port,
+		.sq = req->sq,
+		.ops = req->ops,
+		.p2p_client = req->p2p_client,
+		.kato = le32_to_cpu(c->kato),
+	};
+
+	if (!nvmet_check_transfer_len(req, sizeof(struct nvmf_connect_data)))
+		return;
+
+	d = kmalloc_obj(*d);
+	if (!d) {
+		args.status = NVME_SC_INTERNAL;
+		goto complete;
+	}
+
+	args.status = nvmet_copy_from_sgl(req, 0, d, sizeof(*d));
+	if (args.status)
+		goto out;
+
+	if (c->recfmt != 0) {
+		pr_warn("invalid connect version (%d).\n",
+			le16_to_cpu(c->recfmt));
+		args.error_loc = offsetof(struct nvmf_connect_command, recfmt);
+		args.status = NVME_SC_CONNECT_FORMAT | NVME_STATUS_DNR;
+		goto out;
+	}
+
+	if (unlikely(d->cntlid != cpu_to_le16(0xffff))) {
+		pr_warn("connect attempt for invalid controller ID %#x\n",
+			d->cntlid);
+		args.status = NVME_SC_CONNECT_INVALID_PARAM | NVME_STATUS_DNR;
+		args.result = IPO_IATTR_CONNECT_DATA(cntlid);
+		goto out;
+	}
+
+	d->subsysnqn[NVMF_NQN_FIELD_LEN - 1] = '\0';
+	d->hostnqn[NVMF_NQN_FIELD_LEN - 1] = '\0';
+
+	args.subsysnqn = d->subsysnqn;
+	args.hostnqn = d->hostnqn;
+	args.hostid = &d->hostid;
+	args.kato = le32_to_cpu(c->kato);
+
+	ctrl = nvmet_alloc_ctrl(&args);
+	if (!ctrl)
+		goto out;
+
+	args.status = nvmet_install_queue(ctrl, req);
+	if (args.status) {
+		nvmet_ctrl_put(ctrl);
+		goto out;
+	}
+
+	args.result = cpu_to_le32(nvmet_connect_result(ctrl, req->sq));
+out:
+	kfree(d);
+complete:
+	req->error_loc = args.error_loc;
+	req->cqe->result.u32 = args.result;
+	nvmet_req_complete(req, args.status);
+}
+
+static void nvmet_execute_io_connect(struct nvmet_req *req)
+{
+	struct nvmf_connect_command *c = &req->cmd->connect;
+	struct nvmf_connect_data *d;
+	struct nvmet_ctrl *ctrl;
+	u16 qid = le16_to_cpu(c->qid);
+	u16 status;
+
+	if (!nvmet_check_transfer_len(req, sizeof(struct nvmf_connect_data)))
+		return;
+
+	d = kmalloc_obj(*d);
+	if (!d) {
+		status = NVME_SC_INTERNAL;
+		goto complete;
+	}
+
+	status = nvmet_copy_from_sgl(req, 0, d, sizeof(*d));
+	if (status)
+		goto out;
+
+	if (c->recfmt != 0) {
+		pr_warn("invalid connect version (%d).\n",
+			le16_to_cpu(c->recfmt));
+		status = NVME_SC_CONNECT_FORMAT | NVME_STATUS_DNR;
+		goto out;
+	}
+
+	d->subsysnqn[NVMF_NQN_FIELD_LEN - 1] = '\0';
+	d->hostnqn[NVMF_NQN_FIELD_LEN - 1] = '\0';
+	ctrl = nvmet_ctrl_find_get(d->subsysnqn, d->hostnqn,
+				   le16_to_cpu(d->cntlid), req);
+	if (!ctrl) {
+		status = NVME_SC_CONNECT_INVALID_PARAM | NVME_STATUS_DNR;
+		goto out;
+	}
+
+	if (unlikely(qid > ctrl->max_qid)) {
+		pr_warn("invalid queue id (%d)\n", qid);
+		status = NVME_SC_CONNECT_INVALID_PARAM | NVME_STATUS_DNR;
+		req->cqe->result.u32 = IPO_IATTR_CONNECT_SQE(qid);
+		goto out_ctrl_put;
+	}
+
+	status = nvmet_install_queue(ctrl, req);
+	if (status)
+		goto out_ctrl_put;
+
+	pr_debug("adding queue %d to ctrl %d.\n", qid, ctrl->cntlid);
+	req->cqe->result.u32 = cpu_to_le32(nvmet_connect_result(ctrl, req->sq));
+out:
+	kfree(d);
+complete:
+	nvmet_req_complete(req, status);
+	return;
+
+out_ctrl_put:
+	nvmet_ctrl_put(ctrl);
+	goto out;
+}
+
+u32 nvmet_connect_cmd_data_len(struct nvmet_req *req)
+{
+	struct nvme_command *cmd = req->cmd;
+
+	if (!nvme_is_fabrics(cmd) ||
+	    cmd->fabrics.fctype != nvme_fabrics_type_connect)
+		return 0;
+
+	return sizeof(struct nvmf_connect_data);
+}
+
+u16 nvmet_parse_connect_cmd(struct nvmet_req *req)
+{
+	struct nvme_command *cmd = req->cmd;
+
+	if (!nvme_is_fabrics(cmd)) {
+		pr_debug("invalid command 0x%x on unconnected queue.\n",
+			cmd->fabrics.opcode);
+		req->error_loc = offsetof(struct nvme_common_command, opcode);
+		return NVME_SC_INVALID_OPCODE | NVME_STATUS_DNR;
+	}
+	if (cmd->fabrics.fctype != nvme_fabrics_type_connect) {
+		pr_debug("invalid capsule type 0x%x on unconnected queue.\n",
+			cmd->fabrics.fctype);
+		req->error_loc = offsetof(struct nvmf_common_command, fctype);
+		return NVME_SC_INVALID_OPCODE | NVME_STATUS_DNR;
+	}
+
+	if (cmd->connect.qid == 0)
+		req->execute = nvmet_execute_admin_connect;
+	else
+		req->execute = nvmet_execute_io_connect;
+	return 0;
+}