From 33a154a96e71a34a1bcca9f40da343dbbf7b38b4 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Thu, 1 Oct 2026 14:52:55 +0000 Subject: selftests/bpf: Test packet range of pointers sharing an id 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 Link: https://lore.kernel.org/bpf/20261001145255.855630-2-alexei.starovoitov@gmail.com Signed-off-by: Kumar Kartikeya Dwivedi --- scripts/include/hash.h | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) create mode 100644 scripts/include/hash.h (limited to 'scripts/include/hash.h') diff --git a/scripts/include/hash.h b/scripts/include/hash.h new file mode 100644 index 000000000..efa904368 --- /dev/null +++ b/scripts/include/hash.h @@ -0,0 +1,28 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +#ifndef HASH_H +#define HASH_H + +static inline unsigned int hash_str(const char *s) +{ + /* fnv32 hash */ + unsigned int hash = 2166136261U; + + for (; *s; s++) + hash = (hash ^ *s) * 0x01000193; + return hash; +} + +/* simplified version of functions from include/linux/hash.h */ +#define GOLDEN_RATIO_32 0x61C88647 + +static inline unsigned int hash_32(unsigned int val) +{ + return 0x61C88647 * val; +} + +static inline unsigned int hash_ptr(const void *ptr) +{ + return hash_32((unsigned int)(unsigned long)ptr); +} + +#endif /* HASH_H */ -- cgit v1.3.1