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 --- tools/lib/api/debug.c | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) create mode 100644 tools/lib/api/debug.c (limited to 'tools/lib/api/debug.c') diff --git a/tools/lib/api/debug.c b/tools/lib/api/debug.c new file mode 100644 index 000000000..7708f0558 --- /dev/null +++ b/tools/lib/api/debug.c @@ -0,0 +1,29 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include "debug.h" +#include "debug-internal.h" + +static int __base_pr(const char *format, ...) +{ + va_list args; + int err; + + va_start(args, format); + err = vfprintf(stderr, format, args); + va_end(args); + return err; +} + +libapi_print_fn_t __pr_warn = __base_pr; +libapi_print_fn_t __pr_info = __base_pr; +libapi_print_fn_t __pr_debug; + +void libapi_set_print(libapi_print_fn_t warn, + libapi_print_fn_t info, + libapi_print_fn_t debug) +{ + __pr_warn = warn; + __pr_info = info; + __pr_debug = debug; +} -- cgit v1.3.1