From 6668ed271eaefaa63e686bdfbedaeb7b8e492722 Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Fri, 4 Sep 2026 10:43:19 +0200 Subject: selftests/bpf: Reject graph kptr use after RCU unlock Add a sleepable verifier test that loads a graph-node local kptr in an explicit RCU read-side critical section, then passes its node to bpf_rbtree_remove() after the section ends. Before the verifier fix, the stale NON_OWN_REF flag makes the node look like a live borrowed reference and the program is accepted. After the fix, the pointer is demoted without NON_OWN_REF and the graph kfunc argument is rejected. Also exercise a graph kptr loaded while a spin lock provides implicit RCU protection. The pointer must be invalidated when the lock is released, which guards the required ordering between non-owning-reference invalidation and RCU demotion. Update the existing fault-protected load test state description. The post-unlock pointer no longer carries NON_OWN_REF, but remains readable because the load is rewritten to use BPF_PROBE_MEM. Signed-off-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com Signed-off-by: Alexei Starovoitov --- scripts/extract-ikconfig | 69 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 69 insertions(+) create mode 100755 scripts/extract-ikconfig (limited to 'scripts/extract-ikconfig') diff --git a/scripts/extract-ikconfig b/scripts/extract-ikconfig new file mode 100755 index 000000000..8df33e7d6 --- /dev/null +++ b/scripts/extract-ikconfig @@ -0,0 +1,69 @@ +#!/bin/sh +# ---------------------------------------------------------------------- +# extract-ikconfig - Extract the .config file from a kernel image +# +# This will only work when the kernel was compiled with CONFIG_IKCONFIG. +# +# The obscure use of the "tr" filter is to work around older versions of +# "grep" that report the byte offset of the line instead of the pattern. +# +# (c) 2009,2010 Dick Streefland +# Licensed under the terms of the GNU General Public License. +# ---------------------------------------------------------------------- + +cf1='IKCFG_ST\037\213\010' +cf2='0123456789' + +dump_config() +{ + if pos=`tr "$cf1\n$cf2" "\n$cf2=" < "$1" | grep -abo "^$cf2"` + then + pos=${pos%%:*} + tail -c+$(($pos+8)) "$1" | zcat > $tmp1 2> /dev/null + if [ $? != 1 ] + then # exit status must be 0 or 2 (trailing garbage warning) + cat $tmp1 + exit 0 + fi + fi +} + +try_decompress() +{ + for pos in `tr "$1\n$2" "\n$2=" < "$img" | grep -abo "^$2"` + do + pos=${pos%%:*} + tail -c+$pos "$img" | $3 > $tmp2 2> /dev/null + dump_config $tmp2 + done +} + +# Check invocation: +me=${0##*/} +img=$1 +if [ $# -ne 1 -o ! -s "$img" ] +then + echo "Usage: $me " >&2 + exit 2 +fi + +# Prepare temp files: +tmp1=/tmp/ikconfig$$.1 +tmp2=/tmp/ikconfig$$.2 +trap "rm -f $tmp1 $tmp2" 0 + +# Initial attempt for uncompressed images or objects: +dump_config "$img" + +# That didn't work, so retry after decompression. +try_decompress '\037\213\010' xy gunzip +try_decompress '\3757zXZ\000' abcde unxz +try_decompress 'BZh' xy bunzip2 +try_decompress '\135\0\0\0' xxx unlzma +try_decompress '\211\114\132' xy 'lzop -d' +try_decompress '\002\041\114\030' xyy 'lz4 -d -l' +try_decompress '\050\265\057\375' xxx unzstd + +# Bail out: +echo "$me: Cannot find kernel config." >&2 +exit 1 -- cgit v1.3.1