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, 35 insertions, 0 deletions

diff --git a/include/trace/misc/fsnotify.h b/include/trace/misc/fsnotify.h
new file mode 100644
index 000000000..a201e1bd6
--- /dev/null
+++ b/include/trace/misc/fsnotify.h
@@ -0,0 +1,35 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Display helpers for fsnotify events
+ */
+
+#include <linux/fsnotify_backend.h>
+
+#define show_fsnotify_mask(mask) \
+	__print_flags(mask, "|", \
+		{ FS_ACCESS,		"ACCESS" }, \
+		{ FS_MODIFY,		"MODIFY" }, \
+		{ FS_ATTRIB,		"ATTRIB" }, \
+		{ FS_CLOSE_WRITE,	"CLOSE_WRITE" }, \
+		{ FS_CLOSE_NOWRITE,	"CLOSE_NOWRITE" }, \
+		{ FS_OPEN,		"OPEN" }, \
+		{ FS_MOVED_FROM,	"MOVED_FROM" }, \
+		{ FS_MOVED_TO,		"MOVED_TO" }, \
+		{ FS_CREATE,		"CREATE" }, \
+		{ FS_DELETE,		"DELETE" }, \
+		{ FS_DELETE_SELF,	"DELETE_SELF" }, \
+		{ FS_MOVE_SELF,		"MOVE_SELF" }, \
+		{ FS_OPEN_EXEC,		"OPEN_EXEC" }, \
+		{ FS_UNMOUNT,		"UNMOUNT" }, \
+		{ FS_Q_OVERFLOW,	"Q_OVERFLOW" }, \
+		{ FS_ERROR,		"ERROR" }, \
+		{ FS_OPEN_PERM,		"OPEN_PERM" }, \
+		{ FS_ACCESS_PERM,	"ACCESS_PERM" }, \
+		{ FS_OPEN_EXEC_PERM,	"OPEN_EXEC_PERM" }, \
+		{ FS_PRE_ACCESS,	"PRE_ACCESS" }, \
+		{ FS_MNT_ATTACH,	"MNT_ATTACH" }, \
+		{ FS_MNT_DETACH,	"MNT_DETACH" }, \
+		{ FS_EVENT_ON_CHILD,	"EVENT_ON_CHILD" }, \
+		{ FS_RENAME,		"RENAME" }, \
+		{ FS_DN_MULTISHOT,	"DN_MULTISHOT" }, \
+		{ FS_ISDIR,		"ISDIR" })