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/virtio/virtio-trace/trace-agent.h | 76 +++++++++++++++++++++++++++++++++ 1 file changed, 76 insertions(+) create mode 100644 tools/virtio/virtio-trace/trace-agent.h (limited to 'tools/virtio/virtio-trace/trace-agent.h') diff --git a/tools/virtio/virtio-trace/trace-agent.h b/tools/virtio/virtio-trace/trace-agent.h new file mode 100644 index 000000000..e67885969 --- /dev/null +++ b/tools/virtio/virtio-trace/trace-agent.h @@ -0,0 +1,76 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __TRACE_AGENT_H__ +#define __TRACE_AGENT_H__ +#include +#include + +#define MAX_CPUS 256 +#define PIPE_INIT (1024*1024) + +/* + * agent_info - structure managing total information of guest agent + * @pipe_size: size of pipe (default 1MB) + * @use_stdout: set to true when o option is added (default false) + * @cpus: total number of CPUs + * @ctl_fd: fd of control path, /dev/virtio-ports/agent-ctl-path + * @rw_ti: structure managing information of read/write threads + */ +struct agent_info { + unsigned long pipe_size; + bool use_stdout; + int cpus; + int ctl_fd; + struct rw_thread_info *rw_ti[MAX_CPUS]; +}; + +/* + * rw_thread_info - structure managing a read/write thread a cpu + * @cpu_num: cpu number operating this read/write thread + * @in_fd: fd of reading trace data path in cpu_num + * @out_fd: fd of writing trace data path in cpu_num + * @read_pipe: fd of read pipe + * @write_pipe: fd of write pipe + * @pipe_size: size of pipe (default 1MB) + */ +struct rw_thread_info { + int cpu_num; + int in_fd; + int out_fd; + int read_pipe; + int write_pipe; + unsigned long pipe_size; +}; + +/* use for stopping rw threads */ +extern bool global_sig_receive; + +/* use for notification */ +extern bool global_run_operation; +extern pthread_mutex_t mutex_notify; +extern pthread_cond_t cond_wakeup; + +/* for controller of read/write threads */ +extern int rw_ctl_init(const char *ctl_path); +extern void *rw_ctl_loop(int ctl_fd); + +/* for trace read/write thread */ +extern void *rw_thread_info_new(void); +extern void *rw_thread_init(int cpu, const char *in_path, const char *out_path, + bool stdout_flag, unsigned long pipe_size, + struct rw_thread_info *rw_ti); +extern pthread_t rw_thread_run(struct rw_thread_info *rw_ti); + +static inline void *zalloc(size_t size) +{ + return calloc(1, size); +} + +#define pr_err(format, ...) fprintf(stderr, format, ## __VA_ARGS__) +#define pr_info(format, ...) fprintf(stdout, format, ## __VA_ARGS__) +#ifdef DEBUG +#define pr_debug(format, ...) fprintf(stderr, format, ## __VA_ARGS__) +#else +#define pr_debug(format, ...) do {} while (0) +#endif + +#endif /*__TRACE_AGENT_H__*/ -- cgit v1.3.1