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/objdump-func | 45 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+) create mode 100755 scripts/objdump-func (limited to 'scripts/objdump-func') diff --git a/scripts/objdump-func b/scripts/objdump-func new file mode 100755 index 000000000..7b15b873d --- /dev/null +++ b/scripts/objdump-func @@ -0,0 +1,45 @@ +#!/bin/bash +# SPDX-License-Identifier: GPL-2.0 +# +# Disassemble a single function. +# +# usage: objdump-func [ ...] + +set -o errexit +set -o nounset + +OBJDUMP="${CROSS_COMPILE:-}objdump" + +command -v gawk >/dev/null 2>&1 || die "gawk isn't installed" + +usage() { + echo "usage: objdump-func [ ...]" >&2 + exit 1 +} + +[[ $# -lt 2 ]] && usage + +OBJ=$1; shift +FUNCS=("$@") + +${OBJDUMP} -wdr $OBJ | gawk -M -v _funcs="${FUNCS[*]}" ' + BEGIN { split(_funcs, funcs); } + /^$/ { func_match=0; } + /<.*>:/ { + f = gensub(/.*<(.*)>:/, "\\1", 1); + for (i in funcs) { + # match compiler-added suffixes like ".cold", etc + if (f ~ "^" funcs[i] "(\\..*)?") { + func_match = 1; + base = strtonum("0x" $1); + break; + } + } + } + { + if (func_match) { + addr = strtonum("0x" $1); + printf("%04x ", addr - base); + print; + } + }' -- cgit v1.3.1