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, 322 insertions, 0 deletions

diff --git a/net/ethtool/rings.c b/net/ethtool/rings.c
new file mode 100644
index 000000000..9054c89c5
--- /dev/null
+++ b/net/ethtool/rings.c
@@ -0,0 +1,322 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <net/netdev_queues.h>
+
+#include "common.h"
+#include "netlink.h"
+
+struct rings_req_info {
+	struct ethnl_req_info		base;
+};
+
+struct rings_reply_data {
+	struct ethnl_reply_data		base;
+	struct ethtool_ringparam	ringparam;
+	struct kernel_ethtool_ringparam	kernel_ringparam;
+	u32				supported_ring_params;
+};
+
+#define RINGS_REPDATA(__reply_base) \
+	container_of(__reply_base, struct rings_reply_data, base)
+
+const struct nla_policy ethnl_rings_get_policy[] = {
+	[ETHTOOL_A_RINGS_HEADER]		=
+		NLA_POLICY_NESTED(ethnl_header_policy),
+};
+
+static int rings_prepare_data(const struct ethnl_req_info *req_base,
+			      struct ethnl_reply_data *reply_base,
+			      const struct genl_info *info)
+{
+	struct rings_reply_data *data = RINGS_REPDATA(reply_base);
+	struct net_device *dev = reply_base->dev;
+	int ret;
+
+	if (!dev->ethtool_ops->get_ringparam)
+		return -EOPNOTSUPP;
+
+	data->supported_ring_params = dev->ethtool_ops->supported_ring_params;
+	ret = ethnl_ops_begin(dev);
+	if (ret < 0)
+		return ret;
+
+	data->kernel_ringparam.tcp_data_split = dev->cfg->hds_config;
+	data->kernel_ringparam.hds_thresh = dev->cfg->hds_thresh;
+
+	dev->ethtool_ops->get_ringparam(dev, &data->ringparam,
+					&data->kernel_ringparam, info->extack);
+	ethnl_ops_complete(dev);
+
+	return 0;
+}
+
+static int rings_reply_size(const struct ethnl_req_info *req_base,
+			    const struct ethnl_reply_data *reply_base)
+{
+	return nla_total_size(sizeof(u32)) +	/* _RINGS_RX_MAX */
+	       nla_total_size(sizeof(u32)) +	/* _RINGS_RX_MINI_MAX */
+	       nla_total_size(sizeof(u32)) +	/* _RINGS_RX_JUMBO_MAX */
+	       nla_total_size(sizeof(u32)) +	/* _RINGS_TX_MAX */
+	       nla_total_size(sizeof(u32)) +	/* _RINGS_RX */
+	       nla_total_size(sizeof(u32)) +	/* _RINGS_RX_MINI */
+	       nla_total_size(sizeof(u32)) +	/* _RINGS_RX_JUMBO */
+	       nla_total_size(sizeof(u32)) +	/* _RINGS_TX */
+	       nla_total_size(sizeof(u32)) +	/* _RINGS_RX_BUF_LEN */
+	       nla_total_size(sizeof(u8))  +	/* _RINGS_TCP_DATA_SPLIT */
+	       nla_total_size(sizeof(u32)) +	/* _RINGS_CQE_SIZE */
+	       nla_total_size(sizeof(u8))  +	/* _RINGS_TX_PUSH */
+	       nla_total_size(sizeof(u8))  +	/* _RINGS_RX_PUSH */
+	       nla_total_size(sizeof(u32)) +	/* _RINGS_TX_PUSH_BUF_LEN */
+	       nla_total_size(sizeof(u32)) +	/* _RINGS_TX_PUSH_BUF_LEN_MAX */
+	       nla_total_size(sizeof(u32)) +	/* _RINGS_HDS_THRESH */
+	       nla_total_size(sizeof(u32));	/* _RINGS_HDS_THRESH_MAX*/
+}
+
+static int rings_fill_reply(struct sk_buff *skb,
+			    const struct ethnl_req_info *req_base,
+			    const struct ethnl_reply_data *reply_base)
+{
+	const struct rings_reply_data *data = RINGS_REPDATA(reply_base);
+	const struct kernel_ethtool_ringparam *kr = &data->kernel_ringparam;
+	const struct ethtool_ringparam *ringparam = &data->ringparam;
+	u32 supported_ring_params = data->supported_ring_params;
+
+	WARN_ON(kr->tcp_data_split > ETHTOOL_TCP_DATA_SPLIT_ENABLED);
+
+	if ((ringparam->rx_max_pending &&
+	     (nla_put_u32(skb, ETHTOOL_A_RINGS_RX_MAX,
+			  ringparam->rx_max_pending) ||
+	      nla_put_u32(skb, ETHTOOL_A_RINGS_RX,
+			  ringparam->rx_pending))) ||
+	    (ringparam->rx_mini_max_pending &&
+	     (nla_put_u32(skb, ETHTOOL_A_RINGS_RX_MINI_MAX,
+			  ringparam->rx_mini_max_pending) ||
+	      nla_put_u32(skb, ETHTOOL_A_RINGS_RX_MINI,
+			  ringparam->rx_mini_pending))) ||
+	    (ringparam->rx_jumbo_max_pending &&
+	     (nla_put_u32(skb, ETHTOOL_A_RINGS_RX_JUMBO_MAX,
+			  ringparam->rx_jumbo_max_pending) ||
+	      nla_put_u32(skb, ETHTOOL_A_RINGS_RX_JUMBO,
+			  ringparam->rx_jumbo_pending))) ||
+	    (ringparam->tx_max_pending &&
+	     (nla_put_u32(skb, ETHTOOL_A_RINGS_TX_MAX,
+			  ringparam->tx_max_pending) ||
+	      nla_put_u32(skb, ETHTOOL_A_RINGS_TX,
+			  ringparam->tx_pending)))  ||
+	    (kr->rx_buf_len &&
+	     (nla_put_u32(skb, ETHTOOL_A_RINGS_RX_BUF_LEN, kr->rx_buf_len))) ||
+	    (kr->tcp_data_split &&
+	     (nla_put_u8(skb, ETHTOOL_A_RINGS_TCP_DATA_SPLIT,
+			 kr->tcp_data_split))) ||
+	    (kr->cqe_size &&
+	     (nla_put_u32(skb, ETHTOOL_A_RINGS_CQE_SIZE, kr->cqe_size))) ||
+	    nla_put_u8(skb, ETHTOOL_A_RINGS_TX_PUSH, !!kr->tx_push) ||
+	    nla_put_u8(skb, ETHTOOL_A_RINGS_RX_PUSH, !!kr->rx_push) ||
+	    ((supported_ring_params & ETHTOOL_RING_USE_TX_PUSH_BUF_LEN) &&
+	     (nla_put_u32(skb, ETHTOOL_A_RINGS_TX_PUSH_BUF_LEN_MAX,
+			  kr->tx_push_buf_max_len) ||
+	      nla_put_u32(skb, ETHTOOL_A_RINGS_TX_PUSH_BUF_LEN,
+			  kr->tx_push_buf_len))) ||
+	    ((supported_ring_params & ETHTOOL_RING_USE_HDS_THRS) &&
+	     (nla_put_u32(skb, ETHTOOL_A_RINGS_HDS_THRESH,
+			  kr->hds_thresh) ||
+	      nla_put_u32(skb, ETHTOOL_A_RINGS_HDS_THRESH_MAX,
+			  kr->hds_thresh_max))))
+		return -EMSGSIZE;
+
+	return 0;
+}
+
+/* RINGS_SET */
+
+const struct nla_policy ethnl_rings_set_policy[] = {
+	[ETHTOOL_A_RINGS_HEADER]		=
+		NLA_POLICY_NESTED(ethnl_header_policy),
+	[ETHTOOL_A_RINGS_RX]			= { .type = NLA_U32 },
+	[ETHTOOL_A_RINGS_RX_MINI]		= { .type = NLA_U32 },
+	[ETHTOOL_A_RINGS_RX_JUMBO]		= { .type = NLA_U32 },
+	[ETHTOOL_A_RINGS_TX]			= { .type = NLA_U32 },
+	[ETHTOOL_A_RINGS_RX_BUF_LEN]            = NLA_POLICY_MIN(NLA_U32, 1),
+	[ETHTOOL_A_RINGS_TCP_DATA_SPLIT]	=
+		NLA_POLICY_MAX(NLA_U8, ETHTOOL_TCP_DATA_SPLIT_ENABLED),
+	[ETHTOOL_A_RINGS_CQE_SIZE]		= NLA_POLICY_MIN(NLA_U32, 1),
+	[ETHTOOL_A_RINGS_TX_PUSH]		= NLA_POLICY_MAX(NLA_U8, 1),
+	[ETHTOOL_A_RINGS_RX_PUSH]		= NLA_POLICY_MAX(NLA_U8, 1),
+	[ETHTOOL_A_RINGS_TX_PUSH_BUF_LEN]	= { .type = NLA_U32 },
+	[ETHTOOL_A_RINGS_HDS_THRESH]		= { .type = NLA_U32 },
+};
+
+static int
+ethnl_set_rings_validate(struct ethnl_req_info *req_info,
+			 struct genl_info *info)
+{
+	const struct ethtool_ops *ops = req_info->dev->ethtool_ops;
+	struct nlattr **tb = info->attrs;
+
+	if (tb[ETHTOOL_A_RINGS_RX_BUF_LEN] &&
+	    !(ops->supported_ring_params & ETHTOOL_RING_USE_RX_BUF_LEN)) {
+		NL_SET_ERR_MSG_ATTR(info->extack,
+				    tb[ETHTOOL_A_RINGS_RX_BUF_LEN],
+				    "setting rx buf len not supported");
+		return -EOPNOTSUPP;
+	}
+
+	if (tb[ETHTOOL_A_RINGS_TCP_DATA_SPLIT] &&
+	    !(ops->supported_ring_params & ETHTOOL_RING_USE_TCP_DATA_SPLIT)) {
+		NL_SET_ERR_MSG_ATTR(info->extack,
+				    tb[ETHTOOL_A_RINGS_TCP_DATA_SPLIT],
+				    "setting TCP data split is not supported");
+		return -EOPNOTSUPP;
+	}
+
+	if (tb[ETHTOOL_A_RINGS_HDS_THRESH] &&
+	    !(ops->supported_ring_params & ETHTOOL_RING_USE_HDS_THRS)) {
+		NL_SET_ERR_MSG_ATTR(info->extack,
+				    tb[ETHTOOL_A_RINGS_HDS_THRESH],
+				    "setting hds-thresh is not supported");
+		return -EOPNOTSUPP;
+	}
+
+	if (tb[ETHTOOL_A_RINGS_CQE_SIZE] &&
+	    !(ops->supported_ring_params & ETHTOOL_RING_USE_CQE_SIZE)) {
+		NL_SET_ERR_MSG_ATTR(info->extack,
+				    tb[ETHTOOL_A_RINGS_CQE_SIZE],
+				    "setting cqe size not supported");
+		return -EOPNOTSUPP;
+	}
+
+	if (tb[ETHTOOL_A_RINGS_TX_PUSH] &&
+	    !(ops->supported_ring_params & ETHTOOL_RING_USE_TX_PUSH)) {
+		NL_SET_ERR_MSG_ATTR(info->extack,
+				    tb[ETHTOOL_A_RINGS_TX_PUSH],
+				    "setting tx push not supported");
+		return -EOPNOTSUPP;
+	}
+
+	if (tb[ETHTOOL_A_RINGS_RX_PUSH] &&
+	    !(ops->supported_ring_params & ETHTOOL_RING_USE_RX_PUSH)) {
+		NL_SET_ERR_MSG_ATTR(info->extack,
+				    tb[ETHTOOL_A_RINGS_RX_PUSH],
+				    "setting rx push not supported");
+		return -EOPNOTSUPP;
+	}
+
+	if (tb[ETHTOOL_A_RINGS_TX_PUSH_BUF_LEN] &&
+	    !(ops->supported_ring_params & ETHTOOL_RING_USE_TX_PUSH_BUF_LEN)) {
+		NL_SET_ERR_MSG_ATTR(info->extack,
+				    tb[ETHTOOL_A_RINGS_TX_PUSH_BUF_LEN],
+				    "setting tx push buf len is not supported");
+		return -EOPNOTSUPP;
+	}
+
+	return ops->get_ringparam && ops->set_ringparam ? 1 : -EOPNOTSUPP;
+}
+
+static int
+ethnl_set_rings(struct ethnl_req_info *req_info, struct genl_info *info)
+{
+	struct kernel_ethtool_ringparam kernel_ringparam;
+	struct net_device *dev = req_info->dev;
+	struct ethtool_ringparam ringparam;
+	struct nlattr **tb = info->attrs;
+	const struct nlattr *err_attr;
+	bool mod = false;
+	int ret;
+
+	ethtool_ringparam_get_cfg(dev, &ringparam, &kernel_ringparam,
+				  info->extack);
+
+	ethnl_update_u32(&ringparam.rx_pending, tb[ETHTOOL_A_RINGS_RX], &mod);
+	ethnl_update_u32(&ringparam.rx_mini_pending,
+			 tb[ETHTOOL_A_RINGS_RX_MINI], &mod);
+	ethnl_update_u32(&ringparam.rx_jumbo_pending,
+			 tb[ETHTOOL_A_RINGS_RX_JUMBO], &mod);
+	ethnl_update_u32(&ringparam.tx_pending, tb[ETHTOOL_A_RINGS_TX], &mod);
+	ethnl_update_u32(&kernel_ringparam.rx_buf_len,
+			 tb[ETHTOOL_A_RINGS_RX_BUF_LEN], &mod);
+	ethnl_update_u8(&kernel_ringparam.tcp_data_split,
+			tb[ETHTOOL_A_RINGS_TCP_DATA_SPLIT], &mod);
+	ethnl_update_u32(&kernel_ringparam.cqe_size,
+			 tb[ETHTOOL_A_RINGS_CQE_SIZE], &mod);
+	ethnl_update_u8(&kernel_ringparam.tx_push,
+			tb[ETHTOOL_A_RINGS_TX_PUSH], &mod);
+	ethnl_update_u8(&kernel_ringparam.rx_push,
+			tb[ETHTOOL_A_RINGS_RX_PUSH], &mod);
+	ethnl_update_u32(&kernel_ringparam.tx_push_buf_len,
+			 tb[ETHTOOL_A_RINGS_TX_PUSH_BUF_LEN], &mod);
+	ethnl_update_u32(&kernel_ringparam.hds_thresh,
+			 tb[ETHTOOL_A_RINGS_HDS_THRESH], &mod);
+	if (!mod)
+		return 0;
+
+	if (kernel_ringparam.tcp_data_split == ETHTOOL_TCP_DATA_SPLIT_ENABLED &&
+	    dev_xdp_sb_prog_count(dev)) {
+		NL_SET_ERR_MSG_ATTR(info->extack,
+				    tb[ETHTOOL_A_RINGS_TCP_DATA_SPLIT],
+				    "tcp-data-split can not be enabled with single buffer XDP");
+		return -EINVAL;
+	}
+
+	if (dev_get_min_mp_channel_count(dev)) {
+		if (kernel_ringparam.tcp_data_split !=
+		    ETHTOOL_TCP_DATA_SPLIT_ENABLED) {
+			NL_SET_ERR_MSG(info->extack,
+				       "can't disable tcp-data-split while device has memory provider enabled");
+			return -EINVAL;
+		} else if (kernel_ringparam.hds_thresh) {
+			NL_SET_ERR_MSG(info->extack,
+				       "can't set non-zero hds_thresh while device is memory provider enabled");
+			return -EINVAL;
+		}
+	}
+
+	/* ensure new ring parameters are within limits */
+	if (ringparam.rx_pending > ringparam.rx_max_pending)
+		err_attr = tb[ETHTOOL_A_RINGS_RX];
+	else if (ringparam.rx_mini_pending > ringparam.rx_mini_max_pending)
+		err_attr = tb[ETHTOOL_A_RINGS_RX_MINI];
+	else if (ringparam.rx_jumbo_pending > ringparam.rx_jumbo_max_pending)
+		err_attr = tb[ETHTOOL_A_RINGS_RX_JUMBO];
+	else if (ringparam.tx_pending > ringparam.tx_max_pending)
+		err_attr = tb[ETHTOOL_A_RINGS_TX];
+	else if (kernel_ringparam.hds_thresh > kernel_ringparam.hds_thresh_max)
+		err_attr = tb[ETHTOOL_A_RINGS_HDS_THRESH];
+	else
+		err_attr = NULL;
+	if (err_attr) {
+		NL_SET_ERR_MSG_ATTR(info->extack, err_attr,
+				    "requested ring size exceeds maximum");
+		return -EINVAL;
+	}
+
+	if (kernel_ringparam.tx_push_buf_len > kernel_ringparam.tx_push_buf_max_len) {
+		NL_SET_ERR_MSG_ATTR_FMT(info->extack, tb[ETHTOOL_A_RINGS_TX_PUSH_BUF_LEN],
+					"Requested TX push buffer exceeds the maximum of %u",
+					kernel_ringparam.tx_push_buf_max_len);
+
+		return -EINVAL;
+	}
+
+	dev->cfg_pending->hds_config = kernel_ringparam.tcp_data_split;
+	dev->cfg_pending->hds_thresh = kernel_ringparam.hds_thresh;
+
+	ret = dev->ethtool_ops->set_ringparam(dev, &ringparam,
+					      &kernel_ringparam, info->extack);
+	return ret < 0 ? ret : 1;
+}
+
+const struct ethnl_request_ops ethnl_rings_request_ops = {
+	.request_cmd		= ETHTOOL_MSG_RINGS_GET,
+	.reply_cmd		= ETHTOOL_MSG_RINGS_GET_REPLY,
+	.hdr_attr		= ETHTOOL_A_RINGS_HEADER,
+	.req_info_size		= sizeof(struct rings_req_info),
+	.reply_data_size	= sizeof(struct rings_reply_data),
+
+	.prepare_data		= rings_prepare_data,
+	.reply_size		= rings_reply_size,
+	.fill_reply		= rings_fill_reply,
+
+	.set_validate		= ethnl_set_rings_validate,
+	.set			= ethnl_set_rings,
+	.set_ntf_cmd		= ETHTOOL_MSG_RINGS_NTF,
+};