selftests/bpf: Test packet range of pointers sharing an idgrafted

Add tests where two packet pointers share an id and tightening one
pointer's umax from its var_off would put it less than their constant
distance from the other's umax: with an index & 0x38 capped at 50, the
base pointer keeps umax 50, so the pointer 8 bytes further on must keep
umax 58, even though its known bits allow at most 56.

These refused a valid program or accepted an out-of-bounds access before
the fix:

- check the advanced copy, load through the base: valid, was refused;
- check the base, load the byte at base + 1 through a copy advanced by
  8: was accepted;
- check base + 4, load 4 bytes at base + 2 through base + 8: reads two
  bytes past the checked range, was accepted;
- the same as the second with data_meta pointers checked against data:
  was accepted.

These pass with and without the fix and cover nearby paths:

- subtract an unknown scalar from a checked pointer and load below it
  (the range is kept across a new id);
- reach a load through two paths whose checks cover 8 and 7 bytes after
  the loaded pointer; the second path must not be pruned by the first;
- spill a copy of a pointer, check the pointer, fill the copy and load
  one byte past the checked range: the load is refused, and the copy
  has the range of the check.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20261001145255.855630-2-alexei.starovoitov@gmail.com
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>

1 files changed, 168 insertions, 0 deletions

diff --git a/include/asm-generic/compat.h b/include/asm-generic/compat.h
new file mode 100644
index 000000000..8392caea3
--- /dev/null
+++ b/include/asm-generic/compat.h
@@ -0,0 +1,168 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_GENERIC_COMPAT_H
+#define __ASM_GENERIC_COMPAT_H
+
+#ifndef COMPAT_USER_HZ
+#define COMPAT_USER_HZ		100
+#endif
+
+#ifndef COMPAT_RLIM_INFINITY
+#define COMPAT_RLIM_INFINITY	0xffffffff
+#endif
+
+#ifndef COMPAT_OFF_T_MAX
+#define COMPAT_OFF_T_MAX	0x7fffffff
+#endif
+
+#ifndef compat_arg_u64
+#ifndef CONFIG_CPU_BIG_ENDIAN
+#define compat_arg_u64(name)		u32  name##_lo, u32  name##_hi
+#define compat_arg_u64_dual(name)	u32, name##_lo, u32, name##_hi
+#else
+#define compat_arg_u64(name)		u32  name##_hi, u32  name##_lo
+#define compat_arg_u64_dual(name)	u32, name##_hi, u32, name##_lo
+#endif
+#define compat_arg_u64_glue(name)	(((u64)name##_lo & 0xffffffffUL) | \
+					 ((u64)name##_hi << 32))
+#endif /* compat_arg_u64 */
+
+/* These types are common across all compat ABIs */
+typedef u32 compat_size_t;
+typedef s32 compat_ssize_t;
+typedef s32 compat_clock_t;
+typedef s32 compat_pid_t;
+typedef u32 compat_ino_t;
+typedef s32 compat_off_t;
+typedef s64 compat_loff_t;
+typedef s32 compat_daddr_t;
+typedef s32 compat_timer_t;
+typedef s32 compat_key_t;
+typedef s16 compat_short_t;
+typedef s32 compat_int_t;
+typedef s32 compat_long_t;
+typedef u16 compat_ushort_t;
+typedef u32 compat_uint_t;
+typedef u32 compat_ulong_t;
+typedef u32 compat_uptr_t;
+typedef u32 compat_caddr_t;
+typedef u32 compat_aio_context_t;
+typedef u32 compat_old_sigset_t;
+
+#ifndef __compat_uid_t
+typedef u32 __compat_uid_t;
+typedef u32 __compat_gid_t;
+#endif
+
+#ifndef __compat_uid32_t
+typedef u32 __compat_uid32_t;
+typedef u32 __compat_gid32_t;
+#endif
+
+#ifndef compat_mode_t
+typedef u32 compat_mode_t;
+#endif
+
+#ifdef CONFIG_COMPAT_FOR_U64_ALIGNMENT
+typedef s64 __attribute__((aligned(4))) compat_s64;
+typedef u64 __attribute__((aligned(4))) compat_u64;
+#else
+typedef s64 compat_s64;
+typedef u64 compat_u64;
+#endif
+
+#ifndef _COMPAT_NSIG
+typedef u32 compat_sigset_word;
+#define _COMPAT_NSIG _NSIG
+#define _COMPAT_NSIG_BPW 32
+#endif
+
+#ifndef compat_dev_t
+typedef u32 compat_dev_t;
+#endif
+
+#ifndef compat_ipc_pid_t
+typedef s32 compat_ipc_pid_t;
+#endif
+
+#ifndef compat_fsid_t
+typedef __kernel_fsid_t	compat_fsid_t;
+#endif
+
+#ifndef compat_statfs
+struct compat_statfs {
+	compat_int_t	f_type;
+	compat_int_t	f_bsize;
+	compat_int_t	f_blocks;
+	compat_int_t	f_bfree;
+	compat_int_t	f_bavail;
+	compat_int_t	f_files;
+	compat_int_t	f_ffree;
+	compat_fsid_t	f_fsid;
+	compat_int_t	f_namelen;
+	compat_int_t	f_frsize;
+	compat_int_t	f_flags;
+	compat_int_t	f_spare[4];
+};
+#endif
+
+#ifndef compat_ipc64_perm
+struct compat_ipc64_perm {
+	compat_key_t key;
+	__compat_uid32_t uid;
+	__compat_gid32_t gid;
+	__compat_uid32_t cuid;
+	__compat_gid32_t cgid;
+	compat_mode_t	mode;
+	unsigned char	__pad1[4 - sizeof(compat_mode_t)];
+	compat_ushort_t	seq;
+	compat_ushort_t	__pad2;
+	compat_ulong_t	unused1;
+	compat_ulong_t	unused2;
+};
+
+struct compat_semid64_ds {
+	struct compat_ipc64_perm sem_perm;
+	compat_ulong_t sem_otime;
+	compat_ulong_t sem_otime_high;
+	compat_ulong_t sem_ctime;
+	compat_ulong_t sem_ctime_high;
+	compat_ulong_t sem_nsems;
+	compat_ulong_t __unused3;
+	compat_ulong_t __unused4;
+};
+
+struct compat_msqid64_ds {
+	struct compat_ipc64_perm msg_perm;
+	compat_ulong_t msg_stime;
+	compat_ulong_t msg_stime_high;
+	compat_ulong_t msg_rtime;
+	compat_ulong_t msg_rtime_high;
+	compat_ulong_t msg_ctime;
+	compat_ulong_t msg_ctime_high;
+	compat_ulong_t msg_cbytes;
+	compat_ulong_t msg_qnum;
+	compat_ulong_t msg_qbytes;
+	compat_pid_t   msg_lspid;
+	compat_pid_t   msg_lrpid;
+	compat_ulong_t __unused4;
+	compat_ulong_t __unused5;
+};
+
+struct compat_shmid64_ds {
+	struct compat_ipc64_perm shm_perm;
+	compat_size_t  shm_segsz;
+	compat_ulong_t shm_atime;
+	compat_ulong_t shm_atime_high;
+	compat_ulong_t shm_dtime;
+	compat_ulong_t shm_dtime_high;
+	compat_ulong_t shm_ctime;
+	compat_ulong_t shm_ctime_high;
+	compat_pid_t   shm_cpid;
+	compat_pid_t   shm_lpid;
+	compat_ulong_t shm_nattch;
+	compat_ulong_t __unused4;
+	compat_ulong_t __unused5;
+};
+#endif
+
+#endif