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/stackdelta | 60 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 60 insertions(+) create mode 100755 scripts/stackdelta (limited to 'scripts/stackdelta') diff --git a/scripts/stackdelta b/scripts/stackdelta new file mode 100755 index 000000000..44d2dfd62 --- /dev/null +++ b/scripts/stackdelta @@ -0,0 +1,60 @@ +#!/usr/bin/env perl +# SPDX-License-Identifier: GPL-2.0 + +# Read two files produced by the stackusage script, and show the +# delta between them. +# +# Currently, only shows changes for functions listed in both files. We +# could add an option to show also functions which have vanished or +# appeared (which would often be due to gcc making other inlining +# decisions). +# +# Another possible option would be a minimum absolute value for the +# delta. +# +# A third possibility is for sorting by delta, but that can be +# achieved by piping to sort -k5,5g. + +sub read_stack_usage_file { + my %su; + my $f = shift; + open(my $fh, '<', $f) + or die "cannot open $f: $!"; + while (<$fh>) { + chomp; + my ($file, $func, $size, $type) = split; + # Old versions of gcc (at least 4.7) have an annoying quirk in + # that a (static) function whose name has been changed into + # for example ext4_find_unwritten_pgoff.isra.11 will show up + # in the .su file with a name of just "11". Since such a + # numeric suffix is likely to change across different + # commits/compilers/.configs or whatever else we're trying to + # tweak, we can't really track those functions, so we just + # silently skip them. + # + # Newer gcc (at least 5.0) report the full name, so again, + # since the suffix is likely to change, we strip it. + next if $func =~ m/^[0-9]+$/; + $func =~ s/\..*$//; + # Line numbers are likely to change; strip those. + $file =~ s/:[0-9]+$//; + $su{"${file}\t${func}"} = {size => $size, type => $type}; + } + close($fh); + return \%su; +} + +@ARGV == 2 + or die "usage: $0 "; + +my $old = read_stack_usage_file($ARGV[0]); +my $new = read_stack_usage_file($ARGV[1]); +my @common = sort grep {exists $new->{$_}} keys %$old; +for (@common) { + my $x = $old->{$_}{size}; + my $y = $new->{$_}{size}; + my $delta = $y - $x; + if ($delta) { + printf "%s\t%d\t%d\t%+d\n", $_, $x, $y, $delta; + } +} -- cgit v1.3.1