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, 354 insertions, 0 deletions

diff --git a/arch/sh/mm/cache.c b/arch/sh/mm/cache.c
new file mode 100644
index 000000000..c3f028bed
--- /dev/null
+++ b/arch/sh/mm/cache.c
@@ -0,0 +1,354 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * arch/sh/mm/cache.c
+ *
+ * Copyright (C) 1999, 2000, 2002  Niibe Yutaka
+ * Copyright (C) 2002 - 2010  Paul Mundt
+ */
+#include <linux/mm.h>
+#include <linux/init.h>
+#include <linux/mutex.h>
+#include <linux/fs.h>
+#include <linux/smp.h>
+#include <linux/highmem.h>
+#include <linux/module.h>
+#include <asm/mmu_context.h>
+#include <asm/cacheflush.h>
+
+void (*local_flush_cache_all)(void *args) = cache_noop;
+void (*local_flush_cache_mm)(void *args) = cache_noop;
+void (*local_flush_cache_dup_mm)(void *args) = cache_noop;
+void (*local_flush_cache_page)(void *args) = cache_noop;
+void (*local_flush_cache_range)(void *args) = cache_noop;
+void (*local_flush_dcache_folio)(void *args) = cache_noop;
+void (*local_flush_icache_range)(void *args) = cache_noop;
+void (*local_flush_icache_folio)(void *args) = cache_noop;
+void (*local_flush_cache_sigtramp)(void *args) = cache_noop;
+
+void (*__flush_wback_region)(void *start, int size);
+EXPORT_SYMBOL(__flush_wback_region);
+void (*__flush_purge_region)(void *start, int size);
+EXPORT_SYMBOL(__flush_purge_region);
+void (*__flush_invalidate_region)(void *start, int size);
+EXPORT_SYMBOL(__flush_invalidate_region);
+
+static inline void noop__flush_region(void *start, int size)
+{
+}
+
+static inline void cacheop_on_each_cpu(void (*func) (void *info), void *info,
+                                   int wait)
+{
+	preempt_disable();
+
+	/* Needing IPI for cross-core flush is SHX3-specific. */
+#ifdef CONFIG_CPU_SHX3
+	/*
+	 * It's possible that this gets called early on when IRQs are
+	 * still disabled due to ioremapping by the boot CPU, so don't
+	 * even attempt IPIs unless there are other CPUs online.
+	 */
+	if (num_online_cpus() > 1)
+		smp_call_function(func, info, wait);
+#endif
+
+	func(info);
+
+	preempt_enable();
+}
+
+void copy_to_user_page(struct vm_area_struct *vma, struct page *page,
+		       unsigned long vaddr, void *dst, const void *src,
+		       unsigned long len)
+{
+	struct folio *folio = page_folio(page);
+
+	if (boot_cpu_data.dcache.n_aliases && folio_mapped(folio) &&
+	    test_bit(PG_dcache_clean, &folio->flags.f)) {
+		void *vto = kmap_coherent(page, vaddr) + (vaddr & ~PAGE_MASK);
+		memcpy(vto, src, len);
+		kunmap_coherent(vto);
+	} else {
+		memcpy(dst, src, len);
+		if (boot_cpu_data.dcache.n_aliases)
+			clear_bit(PG_dcache_clean, &folio->flags.f);
+	}
+
+	if (vma->vm_flags & VM_EXEC)
+		flush_cache_page(vma, vaddr, page_to_pfn(page));
+}
+
+void copy_from_user_page(struct vm_area_struct *vma, struct page *page,
+			 unsigned long vaddr, void *dst, const void *src,
+			 unsigned long len)
+{
+	struct folio *folio = page_folio(page);
+
+	if (boot_cpu_data.dcache.n_aliases && folio_mapped(folio) &&
+	    test_bit(PG_dcache_clean, &folio->flags.f)) {
+		void *vfrom = kmap_coherent(page, vaddr) + (vaddr & ~PAGE_MASK);
+		memcpy(dst, vfrom, len);
+		kunmap_coherent(vfrom);
+	} else {
+		memcpy(dst, src, len);
+		if (boot_cpu_data.dcache.n_aliases)
+			clear_bit(PG_dcache_clean, &folio->flags.f);
+	}
+}
+
+void copy_user_highpage(struct page *to, struct page *from,
+			unsigned long vaddr, struct vm_area_struct *vma)
+{
+	struct folio *src = page_folio(from);
+	void *vfrom, *vto;
+
+	vto = kmap_atomic(to);
+
+	if (boot_cpu_data.dcache.n_aliases && folio_mapped(src) &&
+	    test_bit(PG_dcache_clean, &src->flags.f)) {
+		vfrom = kmap_coherent(from, vaddr);
+		copy_page(vto, vfrom);
+		kunmap_coherent(vfrom);
+	} else {
+		vfrom = kmap_atomic(from);
+		copy_page(vto, vfrom);
+		kunmap_atomic(vfrom);
+	}
+
+	if (pages_do_alias((unsigned long)vto, vaddr & PAGE_MASK) ||
+	    (vma->vm_flags & VM_EXEC))
+		__flush_purge_region(vto, PAGE_SIZE);
+
+	kunmap_atomic(vto);
+	/* Make sure this page is cleared on other CPU's too before using it */
+	smp_wmb();
+}
+EXPORT_SYMBOL(copy_user_highpage);
+
+void clear_user_highpage(struct page *page, unsigned long vaddr)
+{
+	void *kaddr = kmap_atomic(page);
+
+	clear_page(kaddr);
+
+	if (pages_do_alias((unsigned long)kaddr, vaddr & PAGE_MASK))
+		__flush_purge_region(kaddr, PAGE_SIZE);
+
+	kunmap_atomic(kaddr);
+}
+EXPORT_SYMBOL(clear_user_highpage);
+
+void __update_cache(struct vm_area_struct *vma,
+		    unsigned long address, pte_t pte)
+{
+	unsigned long pfn = pte_pfn(pte);
+
+	if (!boot_cpu_data.dcache.n_aliases)
+		return;
+
+	if (pfn_valid(pfn)) {
+		struct folio *folio = page_folio(pfn_to_page(pfn));
+		int dirty = !test_and_set_bit(PG_dcache_clean, &folio->flags.f);
+		if (dirty)
+			__flush_purge_region(folio_address(folio),
+						folio_size(folio));
+	}
+}
+
+void __flush_anon_page(struct page *page, unsigned long vmaddr)
+{
+	struct folio *folio = page_folio(page);
+	unsigned long addr = (unsigned long) page_address(page);
+
+	if (pages_do_alias(addr, vmaddr)) {
+		if (boot_cpu_data.dcache.n_aliases && folio_mapped(folio) &&
+		    test_bit(PG_dcache_clean, &folio->flags.f)) {
+			void *kaddr;
+
+			kaddr = kmap_coherent(page, vmaddr);
+			/* XXX.. For now kunmap_coherent() does a purge */
+			/* __flush_purge_region((void *)kaddr, PAGE_SIZE); */
+			kunmap_coherent(kaddr);
+		} else
+			__flush_purge_region(folio_address(folio),
+						folio_size(folio));
+	}
+}
+
+void flush_cache_all(void)
+{
+	cacheop_on_each_cpu(local_flush_cache_all, NULL, 1);
+}
+EXPORT_SYMBOL(flush_cache_all);
+
+void flush_cache_mm(struct mm_struct *mm)
+{
+	if (boot_cpu_data.dcache.n_aliases == 0)
+		return;
+
+	cacheop_on_each_cpu(local_flush_cache_mm, mm, 1);
+}
+
+void flush_cache_dup_mm(struct mm_struct *mm)
+{
+	if (boot_cpu_data.dcache.n_aliases == 0)
+		return;
+
+	cacheop_on_each_cpu(local_flush_cache_dup_mm, mm, 1);
+}
+
+void flush_cache_page(struct vm_area_struct *vma, unsigned long addr,
+		      unsigned long pfn)
+{
+	struct flusher_data data;
+
+	data.vma = vma;
+	data.addr1 = addr;
+	data.addr2 = pfn;
+
+	cacheop_on_each_cpu(local_flush_cache_page, (void *)&data, 1);
+}
+
+void flush_cache_range(struct vm_area_struct *vma, unsigned long start,
+		       unsigned long end)
+{
+	struct flusher_data data;
+
+	data.vma = vma;
+	data.addr1 = start;
+	data.addr2 = end;
+
+	cacheop_on_each_cpu(local_flush_cache_range, (void *)&data, 1);
+}
+EXPORT_SYMBOL(flush_cache_range);
+
+void flush_dcache_folio(struct folio *folio)
+{
+	cacheop_on_each_cpu(local_flush_dcache_folio, folio, 1);
+}
+EXPORT_SYMBOL(flush_dcache_folio);
+
+void flush_icache_range(unsigned long start, unsigned long end)
+{
+	struct flusher_data data;
+
+	data.vma = NULL;
+	data.addr1 = start;
+	data.addr2 = end;
+
+	cacheop_on_each_cpu(local_flush_icache_range, (void *)&data, 1);
+}
+EXPORT_SYMBOL(flush_icache_range);
+
+void flush_icache_pages(struct vm_area_struct *vma, struct page *page,
+		unsigned int nr)
+{
+	/* Nothing uses the VMA, so just pass the folio along */
+	cacheop_on_each_cpu(local_flush_icache_folio, page_folio(page), 1);
+}
+
+void flush_cache_sigtramp(unsigned long address)
+{
+	cacheop_on_each_cpu(local_flush_cache_sigtramp, (void *)address, 1);
+}
+
+static void compute_alias(struct cache_info *c)
+{
+#ifdef CONFIG_MMU
+	c->alias_mask = ((c->sets - 1) << c->entry_shift) & ~(PAGE_SIZE - 1);
+#else
+	c->alias_mask = 0;
+#endif
+	c->n_aliases = c->alias_mask ? (c->alias_mask >> PAGE_SHIFT) + 1 : 0;
+}
+
+static void __init emit_cache_params(void)
+{
+	printk(KERN_NOTICE "I-cache : n_ways=%d n_sets=%d way_incr=%d\n",
+		boot_cpu_data.icache.ways,
+		boot_cpu_data.icache.sets,
+		boot_cpu_data.icache.way_incr);
+	printk(KERN_NOTICE "I-cache : entry_mask=0x%08x alias_mask=0x%08x n_aliases=%d\n",
+		boot_cpu_data.icache.entry_mask,
+		boot_cpu_data.icache.alias_mask,
+		boot_cpu_data.icache.n_aliases);
+	printk(KERN_NOTICE "D-cache : n_ways=%d n_sets=%d way_incr=%d\n",
+		boot_cpu_data.dcache.ways,
+		boot_cpu_data.dcache.sets,
+		boot_cpu_data.dcache.way_incr);
+	printk(KERN_NOTICE "D-cache : entry_mask=0x%08x alias_mask=0x%08x n_aliases=%d\n",
+		boot_cpu_data.dcache.entry_mask,
+		boot_cpu_data.dcache.alias_mask,
+		boot_cpu_data.dcache.n_aliases);
+
+	/*
+	 * Emit Secondary Cache parameters if the CPU has a probed L2.
+	 */
+	if (boot_cpu_data.flags & CPU_HAS_L2_CACHE) {
+		printk(KERN_NOTICE "S-cache : n_ways=%d n_sets=%d way_incr=%d\n",
+			boot_cpu_data.scache.ways,
+			boot_cpu_data.scache.sets,
+			boot_cpu_data.scache.way_incr);
+		printk(KERN_NOTICE "S-cache : entry_mask=0x%08x alias_mask=0x%08x n_aliases=%d\n",
+			boot_cpu_data.scache.entry_mask,
+			boot_cpu_data.scache.alias_mask,
+			boot_cpu_data.scache.n_aliases);
+	}
+}
+
+void __init cpu_cache_init(void)
+{
+	unsigned int cache_disabled = 0;
+
+#ifdef SH_CCR
+	cache_disabled = !(__raw_readl(SH_CCR) & CCR_CACHE_ENABLE);
+#endif
+
+	compute_alias(&boot_cpu_data.icache);
+	compute_alias(&boot_cpu_data.dcache);
+	compute_alias(&boot_cpu_data.scache);
+
+	__flush_wback_region		= noop__flush_region;
+	__flush_purge_region		= noop__flush_region;
+	__flush_invalidate_region	= noop__flush_region;
+
+	/*
+	 * No flushing is necessary in the disabled cache case so we can
+	 * just keep the noop functions in local_flush_..() and __flush_..()
+	 */
+	if (unlikely(cache_disabled))
+		goto skip;
+
+	if (boot_cpu_data.type == CPU_J2) {
+		j2_cache_init();
+	} else if (boot_cpu_data.family == CPU_FAMILY_SH2) {
+		sh2_cache_init();
+	}
+
+	if (boot_cpu_data.family == CPU_FAMILY_SH2A) {
+		sh2a_cache_init();
+	}
+
+	if (boot_cpu_data.family == CPU_FAMILY_SH3) {
+		sh3_cache_init();
+
+		if ((boot_cpu_data.type == CPU_SH7705) &&
+		    (boot_cpu_data.dcache.sets == 512)) {
+			sh7705_cache_init();
+		}
+	}
+
+	if ((boot_cpu_data.family == CPU_FAMILY_SH4) ||
+	    (boot_cpu_data.family == CPU_FAMILY_SH4A) ||
+	    (boot_cpu_data.family == CPU_FAMILY_SH4AL_DSP)) {
+		sh4_cache_init();
+
+		if ((boot_cpu_data.type == CPU_SH7786) ||
+		    (boot_cpu_data.type == CPU_SHX3)) {
+			shx3_cache_init();
+		}
+	}
+
+skip:
+	emit_cache_params();
+}