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, 65 insertions, 0 deletions

diff --git a/arch/mips/boot/ecoff.h b/arch/mips/boot/ecoff.h
new file mode 100644
index 000000000..5be79ebfc
--- /dev/null
+++ b/arch/mips/boot/ecoff.h
@@ -0,0 +1,65 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Some ECOFF definitions.
+ */
+
+#include <stdint.h>
+
+typedef struct filehdr {
+	uint16_t	f_magic;	/* magic number */
+	uint16_t	f_nscns;	/* number of sections */
+	int32_t		f_timdat;	/* time & date stamp */
+	int32_t		f_symptr;	/* file pointer to symbolic header */
+	int32_t		f_nsyms;	/* sizeof(symbolic hdr) */
+	uint16_t	f_opthdr;	/* sizeof(optional hdr) */
+	uint16_t	f_flags;	/* flags */
+} FILHDR;
+#define FILHSZ	sizeof(FILHDR)
+
+#define MIPSEBMAGIC	0x160
+#define MIPSELMAGIC	0x162
+
+typedef struct scnhdr {
+	char		s_name[8];	/* section name */
+	int32_t		s_paddr;	/* physical address, aliased s_nlib */
+	int32_t		s_vaddr;	/* virtual address */
+	int32_t		s_size;		/* section size */
+	int32_t		s_scnptr;	/* file ptr to raw data for section */
+	int32_t		s_relptr;	/* file ptr to relocation */
+	int32_t		s_lnnoptr;	/* file ptr to gp histogram */
+	uint16_t	s_nreloc;	/* number of relocation entries */
+	uint16_t	s_nlnno;	/* number of gp histogram entries */
+	int32_t		s_flags;	/* flags */
+} SCNHDR;
+#define SCNHSZ		sizeof(SCNHDR)
+#define SCNROUND	((int32_t)16)
+
+typedef struct aouthdr {
+	int16_t	magic;		/* see above				*/
+	int16_t	vstamp;		/* version stamp			*/
+	int32_t	tsize;		/* text size in bytes, padded to DW bdry*/
+	int32_t	dsize;		/* initialized data "  "		*/
+	int32_t	bsize;		/* uninitialized data "	  "		*/
+	int32_t	entry;		/* entry pt.				*/
+	int32_t	text_start;	/* base of text used for this file	*/
+	int32_t	data_start;	/* base of data used for this file	*/
+	int32_t	bss_start;	/* base of bss used for this file	*/
+	int32_t	gprmask;	/* general purpose register mask	*/
+	int32_t	cprmask[4];	/* co-processor register masks		*/
+	int32_t	gp_value;	/* the gp value used for this object	*/
+} AOUTHDR;
+#define AOUTHSZ sizeof(AOUTHDR)
+
+#define OMAGIC		0407
+#define NMAGIC		0410
+#define ZMAGIC		0413
+#define SMAGIC		0411
+#define LIBMAGIC	0443
+
+#define N_TXTOFF(f, a) \
+ ((a).magic == ZMAGIC || (a).magic == LIBMAGIC ? 0 : \
+  ((a).vstamp < 23 ? \
+   ((FILHSZ + AOUTHSZ + (f).f_nscns * SCNHSZ + 7) & 0xfffffff8) : \
+   ((FILHSZ + AOUTHSZ + (f).f_nscns * SCNHSZ + SCNROUND-1) & ~(SCNROUND-1)) ) )
+#define N_DATOFF(f, a) \
+  N_TXTOFF(f, a) + (a).tsize;