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 --- include/uapi/asm-generic/ipcbuf.h | 37 +++++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) create mode 100644 include/uapi/asm-generic/ipcbuf.h (limited to 'include/uapi/asm-generic/ipcbuf.h') diff --git a/include/uapi/asm-generic/ipcbuf.h b/include/uapi/asm-generic/ipcbuf.h new file mode 100644 index 000000000..41a01b494 --- /dev/null +++ b/include/uapi/asm-generic/ipcbuf.h @@ -0,0 +1,37 @@ +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ +#ifndef __ASM_GENERIC_IPCBUF_H +#define __ASM_GENERIC_IPCBUF_H + +#include + +/* + * The generic ipc64_perm structure: + * Note extra padding because this structure is passed back and forth + * between kernel and user space. + * + * ipc64_perm was originally meant to be architecture specific, but + * everyone just ended up making identical copies without specific + * optimizations, so we may just as well all use the same one. + * + * Pad space is left for: + * - 32-bit mode_t on architectures that only had 16 bit + * - 32-bit seq + * - 2 miscellaneous 32-bit values + */ + +struct ipc64_perm { + __kernel_key_t key; + __kernel_uid32_t uid; + __kernel_gid32_t gid; + __kernel_uid32_t cuid; + __kernel_gid32_t cgid; + __kernel_mode_t mode; + /* pad if mode_t is u16: */ + unsigned char __pad1[4 - sizeof(__kernel_mode_t)]; + unsigned short seq; + unsigned short __pad2; + __kernel_ulong_t __unused1; + __kernel_ulong_t __unused2; +}; + +#endif /* __ASM_GENERIC_IPCBUF_H */ -- cgit v1.3.1