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/ethtool/plca.c | 271 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 271 insertions(+) create mode 100644 net/ethtool/plca.c (limited to 'net/ethtool/plca.c') diff --git a/net/ethtool/plca.c b/net/ethtool/plca.c new file mode 100644 index 000000000..91f0c4233 --- /dev/null +++ b/net/ethtool/plca.c @@ -0,0 +1,271 @@ +// SPDX-License-Identifier: GPL-2.0-only + +#include +#include + +#include "common.h" +#include "netlink.h" + +struct plca_req_info { + struct ethnl_req_info base; +}; + +struct plca_reply_data { + struct ethnl_reply_data base; + struct phy_plca_cfg plca_cfg; + struct phy_plca_status plca_st; +}; + +// Helpers ------------------------------------------------------------------ // + +#define PLCA_REPDATA(__reply_base) \ + container_of(__reply_base, struct plca_reply_data, base) + +// PLCA get configuration message ------------------------------------------- // + +const struct nla_policy ethnl_plca_get_cfg_policy[] = { + [ETHTOOL_A_PLCA_HEADER] = + NLA_POLICY_NESTED(ethnl_header_policy_phy), +}; + +static void plca_update_sint(int *dst, struct nlattr **tb, u32 attrid, + bool *mod) +{ + const struct nlattr *attr = tb[attrid]; + + if (!attr || + WARN_ON_ONCE(attrid >= ARRAY_SIZE(ethnl_plca_set_cfg_policy))) + return; + + switch (ethnl_plca_set_cfg_policy[attrid].type) { + case NLA_U8: + *dst = nla_get_u8(attr); + break; + case NLA_U32: + *dst = nla_get_u32(attr); + break; + default: + WARN_ON_ONCE(1); + } + + *mod = true; +} + +static int plca_get_cfg_prepare_data(const struct ethnl_req_info *req_base, + struct ethnl_reply_data *reply_base, + const struct genl_info *info) +{ + struct plca_reply_data *data = PLCA_REPDATA(reply_base); + struct net_device *dev = reply_base->dev; + const struct ethtool_phy_ops *ops; + struct nlattr **tb = info->attrs; + struct phy_device *phydev; + int ret; + + phydev = ethnl_req_get_phydev(req_base, tb, ETHTOOL_A_PLCA_HEADER, + info->extack); + // check that the PHY device is available and connected + if (IS_ERR_OR_NULL(phydev)) { + ret = -EOPNOTSUPP; + goto out; + } + + // note: rtnl_lock is held already by ethnl_default_doit + ops = ethtool_phy_ops; + if (!ops || !ops->get_plca_cfg) { + ret = -EOPNOTSUPP; + goto out; + } + + ret = ethnl_ops_begin(dev); + if (ret < 0) + goto out; + + memset(&data->plca_cfg, 0xff, + sizeof_field(struct plca_reply_data, plca_cfg)); + + ret = ops->get_plca_cfg(phydev, &data->plca_cfg); + ethnl_ops_complete(dev); + +out: + return ret; +} + +static int plca_get_cfg_reply_size(const struct ethnl_req_info *req_base, + const struct ethnl_reply_data *reply_base) +{ + return nla_total_size(sizeof(u16)) + /* _VERSION */ + nla_total_size(sizeof(u8)) + /* _ENABLED */ + nla_total_size(sizeof(u32)) + /* _NODE_CNT */ + nla_total_size(sizeof(u32)) + /* _NODE_ID */ + nla_total_size(sizeof(u32)) + /* _TO_TIMER */ + nla_total_size(sizeof(u32)) + /* _BURST_COUNT */ + nla_total_size(sizeof(u32)); /* _BURST_TIMER */ +} + +static int plca_get_cfg_fill_reply(struct sk_buff *skb, + const struct ethnl_req_info *req_base, + const struct ethnl_reply_data *reply_base) +{ + const struct plca_reply_data *data = PLCA_REPDATA(reply_base); + const struct phy_plca_cfg *plca = &data->plca_cfg; + + if ((plca->version >= 0 && + nla_put_u16(skb, ETHTOOL_A_PLCA_VERSION, plca->version)) || + (plca->enabled >= 0 && + nla_put_u8(skb, ETHTOOL_A_PLCA_ENABLED, !!plca->enabled)) || + (plca->node_id >= 0 && + nla_put_u32(skb, ETHTOOL_A_PLCA_NODE_ID, plca->node_id)) || + (plca->node_cnt >= 0 && + nla_put_u32(skb, ETHTOOL_A_PLCA_NODE_CNT, plca->node_cnt)) || + (plca->to_tmr >= 0 && + nla_put_u32(skb, ETHTOOL_A_PLCA_TO_TMR, plca->to_tmr)) || + (plca->burst_cnt >= 0 && + nla_put_u32(skb, ETHTOOL_A_PLCA_BURST_CNT, plca->burst_cnt)) || + (plca->burst_tmr >= 0 && + nla_put_u32(skb, ETHTOOL_A_PLCA_BURST_TMR, plca->burst_tmr))) + return -EMSGSIZE; + + return 0; +}; + +// PLCA set configuration message ------------------------------------------- // + +const struct nla_policy ethnl_plca_set_cfg_policy[] = { + [ETHTOOL_A_PLCA_HEADER] = + NLA_POLICY_NESTED(ethnl_header_policy_phy), + [ETHTOOL_A_PLCA_ENABLED] = NLA_POLICY_MAX(NLA_U8, 1), + [ETHTOOL_A_PLCA_NODE_ID] = NLA_POLICY_MAX(NLA_U32, 255), + [ETHTOOL_A_PLCA_NODE_CNT] = NLA_POLICY_RANGE(NLA_U32, 1, 255), + [ETHTOOL_A_PLCA_TO_TMR] = NLA_POLICY_MAX(NLA_U32, 255), + [ETHTOOL_A_PLCA_BURST_CNT] = NLA_POLICY_MAX(NLA_U32, 255), + [ETHTOOL_A_PLCA_BURST_TMR] = NLA_POLICY_MAX(NLA_U32, 255), +}; + +static int +ethnl_set_plca(struct ethnl_req_info *req_info, struct genl_info *info) +{ + const struct ethtool_phy_ops *ops; + struct nlattr **tb = info->attrs; + struct phy_plca_cfg plca_cfg; + struct phy_device *phydev; + bool mod = false; + int ret; + + phydev = ethnl_req_get_phydev(req_info, tb, ETHTOOL_A_PLCA_HEADER, + info->extack); + // check that the PHY device is available and connected + if (IS_ERR_OR_NULL(phydev)) + return -EOPNOTSUPP; + + ops = ethtool_phy_ops; + if (!ops || !ops->set_plca_cfg) + return -EOPNOTSUPP; + + memset(&plca_cfg, 0xff, sizeof(plca_cfg)); + plca_update_sint(&plca_cfg.enabled, tb, ETHTOOL_A_PLCA_ENABLED, &mod); + plca_update_sint(&plca_cfg.node_id, tb, ETHTOOL_A_PLCA_NODE_ID, &mod); + plca_update_sint(&plca_cfg.node_cnt, tb, ETHTOOL_A_PLCA_NODE_CNT, &mod); + plca_update_sint(&plca_cfg.to_tmr, tb, ETHTOOL_A_PLCA_TO_TMR, &mod); + plca_update_sint(&plca_cfg.burst_cnt, tb, ETHTOOL_A_PLCA_BURST_CNT, + &mod); + plca_update_sint(&plca_cfg.burst_tmr, tb, ETHTOOL_A_PLCA_BURST_TMR, + &mod); + if (!mod) + return 0; + + ret = ops->set_plca_cfg(phydev, &plca_cfg, info->extack); + return ret < 0 ? ret : 1; +} + +const struct ethnl_request_ops ethnl_plca_cfg_request_ops = { + .request_cmd = ETHTOOL_MSG_PLCA_GET_CFG, + .reply_cmd = ETHTOOL_MSG_PLCA_GET_CFG_REPLY, + .hdr_attr = ETHTOOL_A_PLCA_HEADER, + .req_info_size = sizeof(struct plca_req_info), + .reply_data_size = sizeof(struct plca_reply_data), + + .prepare_data = plca_get_cfg_prepare_data, + .reply_size = plca_get_cfg_reply_size, + .fill_reply = plca_get_cfg_fill_reply, + + .set = ethnl_set_plca, + .set_ntf_cmd = ETHTOOL_MSG_PLCA_NTF, +}; + +// PLCA get status message -------------------------------------------------- // + +const struct nla_policy ethnl_plca_get_status_policy[] = { + [ETHTOOL_A_PLCA_HEADER] = + NLA_POLICY_NESTED(ethnl_header_policy_phy), +}; + +static int plca_get_status_prepare_data(const struct ethnl_req_info *req_base, + struct ethnl_reply_data *reply_base, + const struct genl_info *info) +{ + struct plca_reply_data *data = PLCA_REPDATA(reply_base); + struct net_device *dev = reply_base->dev; + const struct ethtool_phy_ops *ops; + struct nlattr **tb = info->attrs; + struct phy_device *phydev; + int ret; + + phydev = ethnl_req_get_phydev(req_base, tb, ETHTOOL_A_PLCA_HEADER, + info->extack); + // check that the PHY device is available and connected + if (IS_ERR_OR_NULL(phydev)) { + ret = -EOPNOTSUPP; + goto out; + } + + // note: rtnl_lock is held already by ethnl_default_doit + ops = ethtool_phy_ops; + if (!ops || !ops->get_plca_status) { + ret = -EOPNOTSUPP; + goto out; + } + + ret = ethnl_ops_begin(dev); + if (ret < 0) + goto out; + + memset(&data->plca_st, 0xff, + sizeof_field(struct plca_reply_data, plca_st)); + + ret = ops->get_plca_status(phydev, &data->plca_st); + ethnl_ops_complete(dev); +out: + return ret; +} + +static int plca_get_status_reply_size(const struct ethnl_req_info *req_base, + const struct ethnl_reply_data *reply_base) +{ + return nla_total_size(sizeof(u8)); /* _STATUS */ +} + +static int plca_get_status_fill_reply(struct sk_buff *skb, + const struct ethnl_req_info *req_base, + const struct ethnl_reply_data *reply_base) +{ + const struct plca_reply_data *data = PLCA_REPDATA(reply_base); + const u8 status = data->plca_st.pst; + + if (nla_put_u8(skb, ETHTOOL_A_PLCA_STATUS, !!status)) + return -EMSGSIZE; + + return 0; +}; + +const struct ethnl_request_ops ethnl_plca_status_request_ops = { + .request_cmd = ETHTOOL_MSG_PLCA_GET_STATUS, + .reply_cmd = ETHTOOL_MSG_PLCA_GET_STATUS_REPLY, + .hdr_attr = ETHTOOL_A_PLCA_HEADER, + .req_info_size = sizeof(struct plca_req_info), + .reply_data_size = sizeof(struct plca_reply_data), + + .prepare_data = plca_get_status_prepare_data, + .reply_size = plca_get_status_reply_size, + .fill_reply = plca_get_status_fill_reply, +}; -- cgit v1.3.1