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/checker-valid.sh | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) create mode 100755 scripts/checker-valid.sh (limited to 'scripts/checker-valid.sh') diff --git a/scripts/checker-valid.sh b/scripts/checker-valid.sh new file mode 100755 index 000000000..625a789ed --- /dev/null +++ b/scripts/checker-valid.sh @@ -0,0 +1,19 @@ +#!/bin/sh -eu +# SPDX-License-Identifier: GPL-2.0 + +[ ! -x "$(command -v "$1")" ] && exit 1 + +tmp_file=$(mktemp) +trap "rm -f $tmp_file" EXIT + +cat << EOF >$tmp_file +static inline int u(const int *q) +{ + __typeof_unqual__(*q) v = *q; + return v; +} +EOF + +# sparse happily exits with 0 on error so validate +# there is none on stderr. Use awk as grep is a pain with sh -e +$@ $tmp_file 2>&1 | awk -v c=1 '/error/{c=0}END{print c}' -- cgit v1.3.1