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, 402 insertions, 0 deletions

diff --git a/net/dsa/devlink.c b/net/dsa/devlink.c
new file mode 100644
index 000000000..ed342f345
--- /dev/null
+++ b/net/dsa/devlink.c
@@ -0,0 +1,402 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * DSA devlink handling
+ */
+
+#include <net/dsa.h>
+#include <net/devlink.h>
+
+#include "devlink.h"
+
+static int dsa_devlink_info_get(struct devlink *dl,
+				struct devlink_info_req *req,
+				struct netlink_ext_ack *extack)
+{
+	struct dsa_switch *ds = dsa_devlink_to_ds(dl);
+
+	if (ds->ops->devlink_info_get)
+		return ds->ops->devlink_info_get(ds, req, extack);
+
+	return -EOPNOTSUPP;
+}
+
+static int dsa_devlink_sb_pool_get(struct devlink *dl,
+				   unsigned int sb_index, u16 pool_index,
+				   struct devlink_sb_pool_info *pool_info)
+{
+	struct dsa_switch *ds = dsa_devlink_to_ds(dl);
+
+	if (!ds->ops->devlink_sb_pool_get)
+		return -EOPNOTSUPP;
+
+	return ds->ops->devlink_sb_pool_get(ds, sb_index, pool_index,
+					    pool_info);
+}
+
+static int dsa_devlink_sb_pool_set(struct devlink *dl, unsigned int sb_index,
+				   u16 pool_index, u32 size,
+				   enum devlink_sb_threshold_type threshold_type,
+				   struct netlink_ext_ack *extack)
+{
+	struct dsa_switch *ds = dsa_devlink_to_ds(dl);
+
+	if (!ds->ops->devlink_sb_pool_set)
+		return -EOPNOTSUPP;
+
+	return ds->ops->devlink_sb_pool_set(ds, sb_index, pool_index, size,
+					    threshold_type, extack);
+}
+
+static int dsa_devlink_sb_port_pool_get(struct devlink_port *dlp,
+					unsigned int sb_index, u16 pool_index,
+					u32 *p_threshold)
+{
+	struct dsa_switch *ds = dsa_devlink_port_to_ds(dlp);
+	int port = dsa_devlink_port_to_port(dlp);
+
+	if (!ds->ops->devlink_sb_port_pool_get)
+		return -EOPNOTSUPP;
+
+	return ds->ops->devlink_sb_port_pool_get(ds, port, sb_index,
+						 pool_index, p_threshold);
+}
+
+static int dsa_devlink_sb_port_pool_set(struct devlink_port *dlp,
+					unsigned int sb_index, u16 pool_index,
+					u32 threshold,
+					struct netlink_ext_ack *extack)
+{
+	struct dsa_switch *ds = dsa_devlink_port_to_ds(dlp);
+	int port = dsa_devlink_port_to_port(dlp);
+
+	if (!ds->ops->devlink_sb_port_pool_set)
+		return -EOPNOTSUPP;
+
+	return ds->ops->devlink_sb_port_pool_set(ds, port, sb_index,
+						 pool_index, threshold, extack);
+}
+
+static int
+dsa_devlink_sb_tc_pool_bind_get(struct devlink_port *dlp,
+				unsigned int sb_index, u16 tc_index,
+				enum devlink_sb_pool_type pool_type,
+				u16 *p_pool_index, u32 *p_threshold)
+{
+	struct dsa_switch *ds = dsa_devlink_port_to_ds(dlp);
+	int port = dsa_devlink_port_to_port(dlp);
+
+	if (!ds->ops->devlink_sb_tc_pool_bind_get)
+		return -EOPNOTSUPP;
+
+	return ds->ops->devlink_sb_tc_pool_bind_get(ds, port, sb_index,
+						    tc_index, pool_type,
+						    p_pool_index, p_threshold);
+}
+
+static int
+dsa_devlink_sb_tc_pool_bind_set(struct devlink_port *dlp,
+				unsigned int sb_index, u16 tc_index,
+				enum devlink_sb_pool_type pool_type,
+				u16 pool_index, u32 threshold,
+				struct netlink_ext_ack *extack)
+{
+	struct dsa_switch *ds = dsa_devlink_port_to_ds(dlp);
+	int port = dsa_devlink_port_to_port(dlp);
+
+	if (!ds->ops->devlink_sb_tc_pool_bind_set)
+		return -EOPNOTSUPP;
+
+	return ds->ops->devlink_sb_tc_pool_bind_set(ds, port, sb_index,
+						    tc_index, pool_type,
+						    pool_index, threshold,
+						    extack);
+}
+
+static int dsa_devlink_sb_occ_snapshot(struct devlink *dl,
+				       unsigned int sb_index)
+{
+	struct dsa_switch *ds = dsa_devlink_to_ds(dl);
+
+	if (!ds->ops->devlink_sb_occ_snapshot)
+		return -EOPNOTSUPP;
+
+	return ds->ops->devlink_sb_occ_snapshot(ds, sb_index);
+}
+
+static int dsa_devlink_sb_occ_max_clear(struct devlink *dl,
+					unsigned int sb_index)
+{
+	struct dsa_switch *ds = dsa_devlink_to_ds(dl);
+
+	if (!ds->ops->devlink_sb_occ_max_clear)
+		return -EOPNOTSUPP;
+
+	return ds->ops->devlink_sb_occ_max_clear(ds, sb_index);
+}
+
+static int dsa_devlink_sb_occ_port_pool_get(struct devlink_port *dlp,
+					    unsigned int sb_index,
+					    u16 pool_index, u32 *p_cur,
+					    u32 *p_max)
+{
+	struct dsa_switch *ds = dsa_devlink_port_to_ds(dlp);
+	int port = dsa_devlink_port_to_port(dlp);
+
+	if (!ds->ops->devlink_sb_occ_port_pool_get)
+		return -EOPNOTSUPP;
+
+	return ds->ops->devlink_sb_occ_port_pool_get(ds, port, sb_index,
+						     pool_index, p_cur, p_max);
+}
+
+static int
+dsa_devlink_sb_occ_tc_port_bind_get(struct devlink_port *dlp,
+				    unsigned int sb_index, u16 tc_index,
+				    enum devlink_sb_pool_type pool_type,
+				    u32 *p_cur, u32 *p_max)
+{
+	struct dsa_switch *ds = dsa_devlink_port_to_ds(dlp);
+	int port = dsa_devlink_port_to_port(dlp);
+
+	if (!ds->ops->devlink_sb_occ_tc_port_bind_get)
+		return -EOPNOTSUPP;
+
+	return ds->ops->devlink_sb_occ_tc_port_bind_get(ds, port,
+							sb_index, tc_index,
+							pool_type, p_cur,
+							p_max);
+}
+
+static const struct devlink_ops dsa_devlink_ops = {
+	.info_get			= dsa_devlink_info_get,
+	.sb_pool_get			= dsa_devlink_sb_pool_get,
+	.sb_pool_set			= dsa_devlink_sb_pool_set,
+	.sb_port_pool_get		= dsa_devlink_sb_port_pool_get,
+	.sb_port_pool_set		= dsa_devlink_sb_port_pool_set,
+	.sb_tc_pool_bind_get		= dsa_devlink_sb_tc_pool_bind_get,
+	.sb_tc_pool_bind_set		= dsa_devlink_sb_tc_pool_bind_set,
+	.sb_occ_snapshot		= dsa_devlink_sb_occ_snapshot,
+	.sb_occ_max_clear		= dsa_devlink_sb_occ_max_clear,
+	.sb_occ_port_pool_get		= dsa_devlink_sb_occ_port_pool_get,
+	.sb_occ_tc_port_bind_get	= dsa_devlink_sb_occ_tc_port_bind_get,
+};
+
+int dsa_devlink_param_get(struct devlink *dl, u32 id,
+			  struct devlink_param_gset_ctx *ctx,
+			  struct netlink_ext_ack *extack)
+{
+	struct dsa_switch *ds = dsa_devlink_to_ds(dl);
+
+	if (!ds->ops->devlink_param_get)
+		return -EOPNOTSUPP;
+
+	return ds->ops->devlink_param_get(ds, id, ctx);
+}
+EXPORT_SYMBOL_GPL(dsa_devlink_param_get);
+
+int dsa_devlink_param_set(struct devlink *dl, u32 id,
+			  struct devlink_param_gset_ctx *ctx,
+			  struct netlink_ext_ack *extack)
+{
+	struct dsa_switch *ds = dsa_devlink_to_ds(dl);
+
+	if (!ds->ops->devlink_param_set)
+		return -EOPNOTSUPP;
+
+	return ds->ops->devlink_param_set(ds, id, ctx);
+}
+EXPORT_SYMBOL_GPL(dsa_devlink_param_set);
+
+int dsa_devlink_params_register(struct dsa_switch *ds,
+				const struct devlink_param *params,
+				size_t params_count)
+{
+	return devlink_params_register(ds->devlink, params, params_count);
+}
+EXPORT_SYMBOL_GPL(dsa_devlink_params_register);
+
+void dsa_devlink_params_unregister(struct dsa_switch *ds,
+				   const struct devlink_param *params,
+				   size_t params_count)
+{
+	devlink_params_unregister(ds->devlink, params, params_count);
+}
+EXPORT_SYMBOL_GPL(dsa_devlink_params_unregister);
+
+int dsa_devlink_resource_register(struct dsa_switch *ds,
+				  const char *resource_name,
+				  u64 resource_size,
+				  u64 resource_id,
+				  u64 parent_resource_id,
+				  const struct devlink_resource_size_params *size_params)
+{
+	int ret;
+
+	devl_lock(ds->devlink);
+	ret = devl_resource_register(ds->devlink, resource_name, resource_size,
+				     resource_id, parent_resource_id,
+				     size_params);
+	devl_unlock(ds->devlink);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(dsa_devlink_resource_register);
+
+void dsa_devlink_resources_unregister(struct dsa_switch *ds)
+{
+	devlink_resources_unregister(ds->devlink);
+}
+EXPORT_SYMBOL_GPL(dsa_devlink_resources_unregister);
+
+void dsa_devlink_resource_occ_get_register(struct dsa_switch *ds,
+					   u64 resource_id,
+					   devlink_resource_occ_get_t *occ_get,
+					   void *occ_get_priv)
+{
+	devl_lock(ds->devlink);
+	devl_resource_occ_get_register(ds->devlink, resource_id, occ_get,
+				       occ_get_priv);
+	devl_unlock(ds->devlink);
+}
+EXPORT_SYMBOL_GPL(dsa_devlink_resource_occ_get_register);
+
+void dsa_devlink_resource_occ_get_unregister(struct dsa_switch *ds,
+					     u64 resource_id)
+{
+	devl_lock(ds->devlink);
+	devl_resource_occ_get_unregister(ds->devlink, resource_id);
+	devl_unlock(ds->devlink);
+}
+EXPORT_SYMBOL_GPL(dsa_devlink_resource_occ_get_unregister);
+
+struct devlink_region *
+dsa_devlink_region_create(struct dsa_switch *ds,
+			  const struct devlink_region_ops *ops,
+			  u32 region_max_snapshots, u64 region_size)
+{
+	return devlink_region_create(ds->devlink, ops, region_max_snapshots,
+				     region_size);
+}
+EXPORT_SYMBOL_GPL(dsa_devlink_region_create);
+
+struct devlink_region *
+dsa_devlink_port_region_create(struct dsa_switch *ds,
+			       int port,
+			       const struct devlink_port_region_ops *ops,
+			       u32 region_max_snapshots, u64 region_size)
+{
+	struct dsa_port *dp = dsa_to_port(ds, port);
+
+	return devlink_port_region_create(&dp->devlink_port, ops,
+					  region_max_snapshots,
+					  region_size);
+}
+EXPORT_SYMBOL_GPL(dsa_devlink_port_region_create);
+
+void dsa_devlink_region_destroy(struct devlink_region *region)
+{
+	devlink_region_destroy(region);
+}
+EXPORT_SYMBOL_GPL(dsa_devlink_region_destroy);
+
+int dsa_port_devlink_setup(struct dsa_port *dp)
+{
+	struct devlink_port *dlp = &dp->devlink_port;
+	struct dsa_switch_tree *dst = dp->ds->dst;
+	struct devlink_port_attrs attrs = {};
+	struct devlink *dl = dp->ds->devlink;
+	struct dsa_switch *ds = dp->ds;
+	const unsigned char *id;
+	unsigned char len;
+	int err;
+
+	memset(dlp, 0, sizeof(*dlp));
+	devlink_port_init(dl, dlp);
+
+	if (ds->ops->port_setup) {
+		err = ds->ops->port_setup(ds, dp->index);
+		if (err)
+			return err;
+	}
+
+	id = (const unsigned char *)&dst->index;
+	len = sizeof(dst->index);
+
+	attrs.phys.port_number = dp->index;
+	memcpy(attrs.switch_id.id, id, len);
+	attrs.switch_id.id_len = len;
+
+	switch (dp->type) {
+	case DSA_PORT_TYPE_UNUSED:
+		attrs.flavour = DEVLINK_PORT_FLAVOUR_UNUSED;
+		break;
+	case DSA_PORT_TYPE_CPU:
+		attrs.flavour = DEVLINK_PORT_FLAVOUR_CPU;
+		break;
+	case DSA_PORT_TYPE_DSA:
+		attrs.flavour = DEVLINK_PORT_FLAVOUR_DSA;
+		break;
+	case DSA_PORT_TYPE_USER:
+		attrs.flavour = DEVLINK_PORT_FLAVOUR_PHYSICAL;
+		break;
+	}
+
+	devlink_port_attrs_set(dlp, &attrs);
+	err = devlink_port_register(dl, dlp, dp->index);
+	if (err) {
+		if (ds->ops->port_teardown)
+			ds->ops->port_teardown(ds, dp->index);
+		return err;
+	}
+
+	return 0;
+}
+
+void dsa_port_devlink_teardown(struct dsa_port *dp)
+{
+	struct devlink_port *dlp = &dp->devlink_port;
+	struct dsa_switch *ds = dp->ds;
+
+	devlink_port_unregister(dlp);
+
+	if (ds->ops->port_teardown)
+		ds->ops->port_teardown(ds, dp->index);
+
+	devlink_port_fini(dlp);
+}
+
+void dsa_switch_devlink_register(struct dsa_switch *ds)
+{
+	devlink_register(ds->devlink);
+}
+
+void dsa_switch_devlink_unregister(struct dsa_switch *ds)
+{
+	devlink_unregister(ds->devlink);
+}
+
+int dsa_switch_devlink_alloc(struct dsa_switch *ds)
+{
+	struct dsa_devlink_priv *dl_priv;
+	struct devlink *dl;
+
+	/* Add the switch to devlink before calling setup, so that setup can
+	 * add dpipe tables
+	 */
+	dl = devlink_alloc(&dsa_devlink_ops, sizeof(*dl_priv), ds->dev);
+	if (!dl)
+		return -ENOMEM;
+
+	ds->devlink = dl;
+
+	dl_priv = devlink_priv(ds->devlink);
+	dl_priv->ds = ds;
+
+	return 0;
+}
+
+void dsa_switch_devlink_free(struct dsa_switch *ds)
+{
+	devlink_free(ds->devlink);
+	ds->devlink = NULL;
+}