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, 157 insertions, 0 deletions

diff --git a/drivers/usb/cdns3/cdns3-debug.h b/drivers/usb/cdns3/cdns3-debug.h
new file mode 100644
index 000000000..4618cfe85
--- /dev/null
+++ b/drivers/usb/cdns3/cdns3-debug.h
@@ -0,0 +1,157 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Cadence USBSS DRD Driver.
+ * Debug header file.
+ *
+ * Copyright (C) 2018-2019 Cadence.
+ *
+ * Author: Pawel Laszczak <pawell@cadence.com>
+ */
+#ifndef __LINUX_CDNS3_DEBUG
+#define __LINUX_CDNS3_DEBUG
+
+#include "core.h"
+
+static inline char *cdns3_decode_usb_irq(char *str,
+					 enum usb_device_speed speed,
+					 u32 usb_ists)
+{
+	int ret;
+
+	ret = sprintf(str, "IRQ %08x = ", usb_ists);
+
+	if (usb_ists & (USB_ISTS_CON2I | USB_ISTS_CONI)) {
+		ret += sprintf(str + ret, "Connection %s\n",
+			       usb_speed_string(speed));
+	}
+	if (usb_ists & USB_ISTS_DIS2I || usb_ists & USB_ISTS_DISI)
+		ret += sprintf(str + ret, "Disconnection ");
+	if (usb_ists & USB_ISTS_L2ENTI)
+		ret += sprintf(str + ret, "suspended ");
+	if (usb_ists & USB_ISTS_L1ENTI)
+		ret += sprintf(str + ret, "L1 enter ");
+	if (usb_ists & USB_ISTS_L1EXTI)
+		ret += sprintf(str + ret, "L1 exit ");
+	if (usb_ists & USB_ISTS_L2ENTI)
+		ret += sprintf(str + ret, "L2 enter ");
+	if (usb_ists & USB_ISTS_L2EXTI)
+		ret += sprintf(str + ret, "L2 exit ");
+	if (usb_ists & USB_ISTS_U3EXTI)
+		ret += sprintf(str + ret, "U3 exit ");
+	if (usb_ists & USB_ISTS_UWRESI)
+		ret += sprintf(str + ret, "Warm Reset ");
+	if (usb_ists & USB_ISTS_UHRESI)
+		ret += sprintf(str + ret, "Hot Reset ");
+	if (usb_ists & USB_ISTS_U2RESI)
+		ret += sprintf(str + ret, "Reset");
+
+	return str;
+}
+
+static inline  char *cdns3_decode_ep_irq(char *str,
+					 u32 ep_sts,
+					 const char *ep_name)
+{
+	int ret;
+
+	ret = sprintf(str, "IRQ for %s: %08x ", ep_name, ep_sts);
+
+	if (ep_sts & EP_STS_SETUP)
+		ret += sprintf(str + ret, "SETUP ");
+	if (ep_sts & EP_STS_IOC)
+		ret += sprintf(str + ret, "IOC ");
+	if (ep_sts & EP_STS_ISP)
+		ret += sprintf(str + ret, "ISP ");
+	if (ep_sts & EP_STS_DESCMIS)
+		ret += sprintf(str + ret, "DESCMIS ");
+	if (ep_sts & EP_STS_STREAMR)
+		ret += sprintf(str + ret, "STREAMR ");
+	if (ep_sts & EP_STS_MD_EXIT)
+		ret += sprintf(str + ret, "MD_EXIT ");
+	if (ep_sts & EP_STS_TRBERR)
+		ret += sprintf(str + ret, "TRBERR ");
+	if (ep_sts & EP_STS_NRDY)
+		ret += sprintf(str + ret, "NRDY ");
+	if (ep_sts & EP_STS_PRIME)
+		ret += sprintf(str + ret, "PRIME ");
+	if (ep_sts & EP_STS_SIDERR)
+		ret += sprintf(str + ret, "SIDERRT ");
+	if (ep_sts & EP_STS_OUTSMM)
+		ret += sprintf(str + ret, "OUTSMM ");
+	if (ep_sts & EP_STS_ISOERR)
+		ret += sprintf(str + ret, "ISOERR ");
+	if (ep_sts & EP_STS_IOT)
+		ret += sprintf(str + ret, "IOT ");
+
+	return str;
+}
+
+static inline char *cdns3_decode_epx_irq(char *str,
+					 char *ep_name,
+					 u32 ep_sts)
+{
+	return cdns3_decode_ep_irq(str, ep_sts, ep_name);
+}
+
+static inline char *cdns3_decode_ep0_irq(char *str,
+					 int dir,
+					 u32 ep_sts)
+{
+	return cdns3_decode_ep_irq(str, ep_sts,
+				   dir ? "ep0IN" : "ep0OUT");
+}
+
+/**
+ * Debug a transfer ring.
+ *
+ * Prints out all TRBs in the endpoint ring, even those after the Link TRB.
+ *.
+ */
+static inline char *cdns3_dbg_ring(struct cdns3_endpoint *priv_ep, char *str)
+{
+	dma_addr_t addr = priv_ep->trb_pool_dma;
+	struct cdns3_trb *trb;
+	int trb_per_sector;
+	int ret = 0;
+	int i;
+
+	trb_per_sector = GET_TRBS_PER_SEGMENT(priv_ep->type);
+
+	trb = &priv_ep->trb_pool[priv_ep->dequeue];
+	ret += sprintf(str + ret, "\n\t\tRing contents for %s:", priv_ep->name);
+
+	ret += sprintf(str + ret,
+		       "\n\t\tRing deq index: %d, trb: %p (virt), 0x%llx (dma)\n",
+		       priv_ep->dequeue, trb,
+		       (unsigned long long)cdns3_trb_virt_to_dma(priv_ep, trb));
+
+	trb = &priv_ep->trb_pool[priv_ep->enqueue];
+	ret += sprintf(str + ret,
+		       "\t\tRing enq index: %d, trb: %p (virt), 0x%llx (dma)\n",
+		       priv_ep->enqueue, trb,
+		       (unsigned long long)cdns3_trb_virt_to_dma(priv_ep, trb));
+
+	ret += sprintf(str + ret,
+		       "\t\tfree trbs: %d, CCS=%d, PCS=%d\n",
+		       priv_ep->free_trbs, priv_ep->ccs, priv_ep->pcs);
+
+	if (trb_per_sector > TRBS_PER_SEGMENT) {
+		sprintf(str + ret, "\t\tTransfer ring %d too big\n",
+			trb_per_sector);
+		return str;
+	}
+
+	for (i = 0; i < trb_per_sector; ++i) {
+		trb = &priv_ep->trb_pool[i];
+		ret += sprintf(str + ret,
+			"\t\t@%pad %08x %08x %08x\n", &addr,
+			le32_to_cpu(trb->buffer),
+			le32_to_cpu(trb->length),
+			le32_to_cpu(trb->control));
+		addr += sizeof(*trb);
+	}
+
+	return str;
+}
+
+#endif /*__LINUX_CDNS3_DEBUG*/