bpf: mark a NULL kfunc argument precisegrafted

check_kfunc_arg() allows bpf_register_is_null() for nullable arguments
w/o marking the underlying scalar register precise. Hence a checkpoint
created on such a path would prune against arbitrary scalar value.

Fixes: 3bda08b63670 ("bpf: Allow NULL buffers in bpf_dynptr_slice(_rw)")
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260904-register-is-null-precise-fixes-v1-5-0f5a360ff15d@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 119 insertions, 0 deletions

diff --git a/arch/mips/mm/pgtable-64.c b/arch/mips/mm/pgtable-64.c
new file mode 100644
index 000000000..b24f865de
--- /dev/null
+++ b/arch/mips/mm/pgtable-64.c
@@ -0,0 +1,119 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 1999, 2000 by Silicon Graphics
+ * Copyright (C) 2003 by Ralf Baechle
+ */
+#include <linux/export.h>
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <asm/fixmap.h>
+#include <asm/pgalloc.h>
+#include <asm/tlbflush.h>
+
+void pgd_init(void *addr)
+{
+	unsigned long *p, *end;
+	unsigned long entry;
+
+#if !defined(__PAGETABLE_PUD_FOLDED)
+	entry = (unsigned long)invalid_pud_table;
+#elif !defined(__PAGETABLE_PMD_FOLDED)
+	entry = (unsigned long)invalid_pmd_table;
+#else
+	entry = (unsigned long)invalid_pte_table;
+#endif
+
+	p = (unsigned long *) addr;
+	end = p + PTRS_PER_PGD;
+
+	do {
+		p[0] = entry;
+		p[1] = entry;
+		p[2] = entry;
+		p[3] = entry;
+		p[4] = entry;
+		p += 8;
+		p[-3] = entry;
+		p[-2] = entry;
+		p[-1] = entry;
+	} while (p != end);
+}
+
+#ifndef __PAGETABLE_PMD_FOLDED
+void pmd_init(void *addr)
+{
+	unsigned long *p, *end;
+	unsigned long pagetable = (unsigned long)invalid_pte_table;
+
+	p = (unsigned long *)addr;
+	end = p + PTRS_PER_PMD;
+
+	do {
+		p[0] = pagetable;
+		p[1] = pagetable;
+		p[2] = pagetable;
+		p[3] = pagetable;
+		p[4] = pagetable;
+		p += 8;
+		p[-3] = pagetable;
+		p[-2] = pagetable;
+		p[-1] = pagetable;
+	} while (p != end);
+}
+EXPORT_SYMBOL_GPL(pmd_init);
+#endif
+
+#ifndef __PAGETABLE_PUD_FOLDED
+void pud_init(void *addr)
+{
+	unsigned long *p, *end;
+	unsigned long pagetable = (unsigned long)invalid_pmd_table;
+
+	p = (unsigned long *)addr;
+	end = p + PTRS_PER_PUD;
+
+	do {
+		p[0] = pagetable;
+		p[1] = pagetable;
+		p[2] = pagetable;
+		p[3] = pagetable;
+		p[4] = pagetable;
+		p += 8;
+		p[-3] = pagetable;
+		p[-2] = pagetable;
+		p[-1] = pagetable;
+	} while (p != end);
+}
+#endif
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+void set_pmd_at(struct mm_struct *mm, unsigned long addr,
+		pmd_t *pmdp, pmd_t pmd)
+{
+	*pmdp = pmd;
+}
+#endif
+
+void __init pagetable_init(void)
+{
+	unsigned long vaddr;
+	pgd_t *pgd_base;
+
+	/* Initialize the entire pgd.  */
+	pgd_init(swapper_pg_dir);
+#ifndef __PAGETABLE_PUD_FOLDED
+	pud_init(invalid_pud_table);
+#endif
+#ifndef __PAGETABLE_PMD_FOLDED
+	pmd_init(invalid_pmd_table);
+#endif
+	pgd_base = swapper_pg_dir;
+	/*
+	 * Fixed mappings:
+	 */
+	vaddr = __fix_to_virt(__end_of_fixed_addresses - 1) & PMD_MASK;
+	fixrange_init(vaddr, vaddr + FIXADDR_SIZE, pgd_base);
+}