From a5f7a5bb3b7f28ba7e4fa246775b29a0e5537255 Mon Sep 17 00:00:00 2001 From: Jinke Han Date: Tue, 8 Sep 2026 15:37:42 +0800 Subject: x86/kprobes: Fix crash when probing CS CALL instructions 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) Signed-off-by: Jinke Han Signed-off-by: Ingo Molnar Reviewed-by: Masami Hiramatsu (Google) Acked-by: Yafang Shao Acked-by: Borislav Petkov Cc: Peter Zijlstra Link: https://patch.msgid.link/20260908073742.GA10517@didi-ThinkCentre-M920t-N000 --- net/devlink/netlink.c | 476 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 476 insertions(+) create mode 100644 net/devlink/netlink.c (limited to 'net/devlink/netlink.c') diff --git a/net/devlink/netlink.c b/net/devlink/netlink.c new file mode 100644 index 000000000..a8eda727b --- /dev/null +++ b/net/devlink/netlink.c @@ -0,0 +1,476 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (c) 2016 Mellanox Technologies. All rights reserved. + * Copyright (c) 2016 Jiri Pirko + */ + +#include +#include + +#include "devl_internal.h" + +#define DEVLINK_NL_FLAG_NEED_PORT BIT(0) +#define DEVLINK_NL_FLAG_NEED_DEVLINK_OR_PORT BIT(1) +#define DEVLINK_NL_FLAG_NEED_DEV_LOCK BIT(2) +#define DEVLINK_NL_FLAG_OPTIONAL_PARENT_DEV BIT(3) + +static const struct genl_multicast_group devlink_nl_mcgrps[] = { + [DEVLINK_MCGRP_CONFIG] = { .name = DEVLINK_GENL_MCGRP_CONFIG_NAME }, +}; + +struct devlink_nl_sock_priv { + struct devlink_obj_desc __rcu *flt; + spinlock_t flt_lock; /* Protects flt. */ +}; + +static void devlink_nl_sock_priv_init(void *priv) +{ + struct devlink_nl_sock_priv *sk_priv = priv; + + spin_lock_init(&sk_priv->flt_lock); +} + +static void devlink_nl_sock_priv_destroy(void *priv) +{ + struct devlink_nl_sock_priv *sk_priv = priv; + struct devlink_obj_desc *flt; + + flt = rcu_dereference_protected(sk_priv->flt, true); + kfree_rcu(flt, rcu); +} + +int devlink_nl_notify_filter_set_doit(struct sk_buff *skb, + struct genl_info *info) +{ + struct devlink_nl_sock_priv *sk_priv; + struct nlattr **attrs = info->attrs; + struct devlink_obj_desc *flt; + size_t data_offset = 0; + size_t data_size = 0; + char *pos; + + if (attrs[DEVLINK_ATTR_BUS_NAME]) + data_size = size_add(data_size, + nla_len(attrs[DEVLINK_ATTR_BUS_NAME]) + 1); + if (attrs[DEVLINK_ATTR_DEV_NAME]) + data_size = size_add(data_size, + nla_len(attrs[DEVLINK_ATTR_DEV_NAME]) + 1); + + flt = kzalloc(size_add(sizeof(*flt), data_size), GFP_KERNEL); + if (!flt) + return -ENOMEM; + + pos = (char *) flt->data; + if (attrs[DEVLINK_ATTR_BUS_NAME]) { + data_offset += nla_strscpy(pos, + attrs[DEVLINK_ATTR_BUS_NAME], + data_size) + 1; + flt->bus_name = pos; + pos += data_offset; + } + if (attrs[DEVLINK_ATTR_DEV_NAME]) { + nla_strscpy(pos, attrs[DEVLINK_ATTR_DEV_NAME], + data_size - data_offset); + flt->dev_name = pos; + } + + if (attrs[DEVLINK_ATTR_INDEX]) { + flt->devlink_index = nla_get_uint(attrs[DEVLINK_ATTR_INDEX]); + flt->devlink_index_valid = true; + } + + if (attrs[DEVLINK_ATTR_PORT_INDEX]) { + flt->port_index = nla_get_u32(attrs[DEVLINK_ATTR_PORT_INDEX]); + flt->port_index_valid = true; + } + + /* Don't attach empty filter. */ + if (!flt->bus_name && !flt->dev_name && + !flt->devlink_index_valid && !flt->port_index_valid) { + kfree(flt); + flt = NULL; + } + + sk_priv = genl_sk_priv_get(&devlink_nl_family, NETLINK_CB(skb).sk); + if (IS_ERR(sk_priv)) { + kfree(flt); + return PTR_ERR(sk_priv); + } + spin_lock(&sk_priv->flt_lock); + flt = rcu_replace_pointer(sk_priv->flt, flt, + lockdep_is_held(&sk_priv->flt_lock)); + spin_unlock(&sk_priv->flt_lock); + kfree_rcu(flt, rcu); + return 0; +} + +static bool devlink_obj_desc_match(const struct devlink_obj_desc *desc, + const struct devlink_obj_desc *flt) +{ + if (desc->devlink_index_valid && flt->devlink_index_valid && + desc->devlink_index != flt->devlink_index) + return false; + if (desc->bus_name && flt->bus_name && + strcmp(desc->bus_name, flt->bus_name)) + return false; + if (desc->dev_name && flt->dev_name && + strcmp(desc->dev_name, flt->dev_name)) + return false; + if (desc->port_index_valid && flt->port_index_valid && + desc->port_index != flt->port_index) + return false; + return true; +} + +int devlink_nl_notify_filter(struct sock *dsk, struct sk_buff *skb, void *data) +{ + struct devlink_obj_desc *desc = data; + struct devlink_nl_sock_priv *sk_priv; + struct devlink_obj_desc *flt; + int ret = 0; + + rcu_read_lock(); + sk_priv = __genl_sk_priv_get(&devlink_nl_family, dsk); + if (!IS_ERR_OR_NULL(sk_priv)) { + flt = rcu_dereference(sk_priv->flt); + if (flt) + ret = !devlink_obj_desc_match(desc, flt); + } + rcu_read_unlock(); + return ret; +} + +int devlink_nl_put_nested_handle(struct sk_buff *msg, struct net *net, + struct devlink *devlink, int attrtype) +{ + struct nlattr *nested_attr; + struct net *devl_net; + + nested_attr = nla_nest_start(msg, attrtype); + if (!nested_attr) + return -EMSGSIZE; + if (devlink_nl_put_handle(msg, devlink)) + goto nla_put_failure; + + rcu_read_lock(); + devl_net = read_pnet_rcu(&devlink->_net); + if (!net_eq(net, devl_net)) { + int id = peernet2id_alloc(net, devl_net, GFP_ATOMIC); + + rcu_read_unlock(); + if (nla_put_s32(msg, DEVLINK_ATTR_NETNS_ID, id)) + return -EMSGSIZE; + } else { + rcu_read_unlock(); + } + + nla_nest_end(msg, nested_attr); + return 0; + +nla_put_failure: + nla_nest_cancel(msg, nested_attr); + return -EMSGSIZE; +} + +int devlink_nl_msg_reply_and_new(struct sk_buff **msg, struct genl_info *info) +{ + int err; + + if (*msg) { + err = genlmsg_reply(*msg, info); + if (err) + return err; + } + *msg = genlmsg_new(GENLMSG_DEFAULT_SIZE, GFP_KERNEL); + if (!*msg) + return -ENOMEM; + return 0; +} + +struct devlink * +devlink_get_from_attrs_lock(struct net *net, struct nlattr **attrs, + bool dev_lock) +{ + struct devlink *devlink; + unsigned long index; + char *busname; + char *devname; + + if (attrs[DEVLINK_ATTR_INDEX]) { + if (attrs[DEVLINK_ATTR_BUS_NAME] || + attrs[DEVLINK_ATTR_DEV_NAME]) + return ERR_PTR(-EINVAL); + index = nla_get_u32(attrs[DEVLINK_ATTR_INDEX]); + devlink = devlinks_xa_lookup_get(net, index); + if (!devlink) + return ERR_PTR(-ENODEV); + goto found; + } + + if (!attrs[DEVLINK_ATTR_BUS_NAME] || !attrs[DEVLINK_ATTR_DEV_NAME]) + return ERR_PTR(-EINVAL); + + busname = nla_data(attrs[DEVLINK_ATTR_BUS_NAME]); + devname = nla_data(attrs[DEVLINK_ATTR_DEV_NAME]); + + if (!strcmp(busname, DEVLINK_INDEX_BUS_NAME)) { + if (kstrtoul(devname, 10, &index)) + return ERR_PTR(-ENODEV); + devlink = devlinks_xa_lookup_get(net, index); + if (!devlink) + return ERR_PTR(-ENODEV); + goto found; + } + + devlinks_xa_for_each_registered_get(net, index, devlink) { + if (strcmp(devlink_bus_name(devlink), busname) == 0 && + strcmp(devlink_dev_name(devlink), devname) == 0) + goto found; + devlink_put(devlink); + } + + return ERR_PTR(-ENODEV); + +found: + devl_dev_lock(devlink, dev_lock); + if (devl_is_registered(devlink)) + return devlink; + devl_dev_unlock(devlink, dev_lock); + devlink_put(devlink); + return ERR_PTR(-ENODEV); +} + +struct devlink * +devlink_get_parent_from_attrs_lock(struct net *net, struct nlattr **attrs) +{ + unsigned int maxtype = ARRAY_SIZE(devlink_dl_parent_dev_nl_policy) - 1; + struct devlink *devlink; + struct nlattr **tb; + int err; + + if (!attrs[DEVLINK_ATTR_PARENT_DEV]) + return ERR_PTR(-EINVAL); + + tb = kzalloc_objs(*tb, maxtype + 1); + if (!tb) + return ERR_PTR(-ENOMEM); + + err = nla_parse_nested(tb, maxtype, attrs[DEVLINK_ATTR_PARENT_DEV], + devlink_dl_parent_dev_nl_policy, NULL); + if (err) + goto out; + + devlink = devlink_get_from_attrs_lock(net, tb, false); + kfree(tb); + return devlink; +out: + kfree(tb); + return ERR_PTR(err); +} + +static int __devlink_nl_pre_doit(struct sk_buff *skb, struct genl_info *info, + u8 flags) +{ + bool parent_dev = flags & DEVLINK_NL_FLAG_OPTIONAL_PARENT_DEV; + bool dev_lock = flags & DEVLINK_NL_FLAG_NEED_DEV_LOCK; + struct devlink *devlink, *parent_devlink = NULL; + struct net *net = genl_info_net(info); + struct nlattr **attrs = info->attrs; + struct devlink_port *devlink_port; + int err; + + if (parent_dev && attrs[DEVLINK_ATTR_PARENT_DEV]) { + parent_devlink = devlink_get_parent_from_attrs_lock(net, attrs); + if (IS_ERR(parent_devlink)) + return PTR_ERR(parent_devlink); + devlink_nl_ctx(info)->parent_devlink = parent_devlink; + /* Drop the parent devlink lock but don't release the reference. + * This will keep it alive until the end of the request. + */ + devl_unlock(parent_devlink); + } + + devlink = devlink_get_from_attrs_lock(net, attrs, dev_lock); + if (IS_ERR(devlink)) { + err = PTR_ERR(devlink); + goto parent_put; + } + devlink_nl_ctx(info)->devlink = devlink; + if (flags & DEVLINK_NL_FLAG_NEED_PORT) { + devlink_port = devlink_port_get_from_info(devlink, info); + if (IS_ERR(devlink_port)) { + err = PTR_ERR(devlink_port); + goto unlock; + } + devlink_nl_ctx(info)->devlink_port = devlink_port; + } else if (flags & DEVLINK_NL_FLAG_NEED_DEVLINK_OR_PORT) { + devlink_port = devlink_port_get_from_info(devlink, info); + if (!IS_ERR(devlink_port)) + devlink_nl_ctx(info)->devlink_port = devlink_port; + } + return 0; + +unlock: + devl_dev_unlock(devlink, dev_lock); + devlink_put(devlink); +parent_put: + if (parent_dev && parent_devlink) + devlink_put(parent_devlink); + return err; +} + +int devlink_nl_pre_doit(const struct genl_split_ops *ops, + struct sk_buff *skb, struct genl_info *info) +{ + return __devlink_nl_pre_doit(skb, info, 0); +} + +int devlink_nl_pre_doit_port(const struct genl_split_ops *ops, + struct sk_buff *skb, struct genl_info *info) +{ + return __devlink_nl_pre_doit(skb, info, DEVLINK_NL_FLAG_NEED_PORT); +} + +int devlink_nl_pre_doit_dev_lock(const struct genl_split_ops *ops, + struct sk_buff *skb, struct genl_info *info) +{ + return __devlink_nl_pre_doit(skb, info, DEVLINK_NL_FLAG_NEED_DEV_LOCK); +} + +int devlink_nl_pre_doit_port_optional(const struct genl_split_ops *ops, + struct sk_buff *skb, + struct genl_info *info) +{ + return __devlink_nl_pre_doit(skb, info, DEVLINK_NL_FLAG_NEED_DEVLINK_OR_PORT); +} + +int devlink_nl_pre_doit_parent_dev_optional(const struct genl_split_ops *ops, + struct sk_buff *skb, + struct genl_info *info) +{ + return __devlink_nl_pre_doit(skb, info, + DEVLINK_NL_FLAG_OPTIONAL_PARENT_DEV); +} + +static void __devlink_nl_post_doit(struct sk_buff *skb, struct genl_info *info, + u8 flags) +{ + bool dev_lock = flags & DEVLINK_NL_FLAG_NEED_DEV_LOCK; + struct devlink *devlink; + + devlink = devlink_nl_ctx(info)->devlink; + devl_dev_unlock(devlink, dev_lock); + devlink_put(devlink); + if (devlink_nl_ctx(info)->parent_devlink) + devlink_put(devlink_nl_ctx(info)->parent_devlink); +} + +void devlink_nl_post_doit(const struct genl_split_ops *ops, + struct sk_buff *skb, struct genl_info *info) +{ + __devlink_nl_post_doit(skb, info, 0); +} + +void +devlink_nl_post_doit_dev_lock(const struct genl_split_ops *ops, + struct sk_buff *skb, struct genl_info *info) +{ + __devlink_nl_post_doit(skb, info, DEVLINK_NL_FLAG_NEED_DEV_LOCK); +} + +void +devlink_nl_post_doit_parent_dev_optional(const struct genl_split_ops *ops, + struct sk_buff *skb, + struct genl_info *info) +{ + __devlink_nl_post_doit(skb, info, DEVLINK_NL_FLAG_OPTIONAL_PARENT_DEV); +} + +static int devlink_nl_inst_single_dumpit(struct sk_buff *msg, + struct netlink_callback *cb, int flags, + devlink_nl_dump_one_func_t *dump_one, + struct nlattr **attrs) +{ + struct devlink *devlink; + int err; + + devlink = devlink_get_from_attrs_lock(sock_net(msg->sk), attrs, false); + if (IS_ERR(devlink)) + return PTR_ERR(devlink); + err = dump_one(msg, devlink, cb, flags | NLM_F_DUMP_FILTERED); + + devl_unlock(devlink); + devlink_put(devlink); + + if (err != -EMSGSIZE) + return err; + return msg->len; +} + +static int devlink_nl_inst_iter_dumpit(struct sk_buff *msg, + struct netlink_callback *cb, int flags, + devlink_nl_dump_one_func_t *dump_one) +{ + struct devlink_nl_dump_state *state = devlink_dump_state(cb); + struct devlink *devlink; + int err = 0; + + while ((devlink = devlinks_xa_find_get(sock_net(msg->sk), + &state->instance))) { + devl_lock(devlink); + + if (devl_is_registered(devlink)) + err = dump_one(msg, devlink, cb, flags); + else + err = 0; + + devl_unlock(devlink); + devlink_put(devlink); + + if (err) + break; + + state->instance++; + + /* restart sub-object walk for the next instance */ + state->idx = 0; + state->port_ctx.index = 0; + state->port_ctx.index_valid = false; + } + + if (err != -EMSGSIZE) + return err; + return msg->len; +} + +int devlink_nl_dumpit(struct sk_buff *msg, struct netlink_callback *cb, + devlink_nl_dump_one_func_t *dump_one) +{ + const struct genl_info *info = genl_info_dump(cb); + struct nlattr **attrs = info->attrs; + int flags = NLM_F_MULTI; + + if (attrs && + (attrs[DEVLINK_ATTR_BUS_NAME] || attrs[DEVLINK_ATTR_DEV_NAME] || + attrs[DEVLINK_ATTR_INDEX])) + return devlink_nl_inst_single_dumpit(msg, cb, flags, dump_one, + attrs); + else + return devlink_nl_inst_iter_dumpit(msg, cb, flags, dump_one); +} + +struct genl_family devlink_nl_family __ro_after_init = { + .name = DEVLINK_GENL_NAME, + .version = DEVLINK_GENL_VERSION, + .netnsok = true, + .parallel_ops = true, + .module = THIS_MODULE, + .split_ops = devlink_nl_ops, + .n_split_ops = ARRAY_SIZE(devlink_nl_ops), + .resv_start_op = DEVLINK_CMD_SELFTESTS_RUN + 1, + .mcgrps = devlink_nl_mcgrps, + .n_mcgrps = ARRAY_SIZE(devlink_nl_mcgrps), + .sock_priv_size = sizeof(struct devlink_nl_sock_priv), + .sock_priv_init = devlink_nl_sock_priv_init, + .sock_priv_destroy = devlink_nl_sock_priv_destroy, +}; -- cgit v1.3.1