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 --- fs/minix/file.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 54 insertions(+) create mode 100644 fs/minix/file.c (limited to 'fs/minix/file.c') diff --git a/fs/minix/file.c b/fs/minix/file.c new file mode 100644 index 000000000..02aabbdb5 --- /dev/null +++ b/fs/minix/file.c @@ -0,0 +1,54 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * linux/fs/minix/file.c + * + * Copyright (C) 1991, 1992 Linus Torvalds + * + * minix regular file handling primitives + */ + +#include +#include "minix.h" + +/* + * We have mostly NULLs here: the current defaults are OK for + * the minix filesystem. + */ +const struct file_operations minix_file_operations = { + .llseek = generic_file_llseek, + .read_iter = generic_file_read_iter, + .write_iter = generic_file_write_iter, + .mmap_prepare = generic_file_mmap_prepare, + .fsync = simple_fsync, + .splice_read = filemap_splice_read, +}; + +static int minix_setattr(struct mnt_idmap *idmap, + struct dentry *dentry, struct iattr *attr) +{ + struct inode *inode = d_inode(dentry); + int error; + + error = setattr_prepare(&nop_mnt_idmap, dentry, attr); + if (error) + return error; + + if ((attr->ia_valid & ATTR_SIZE) && + attr->ia_size != i_size_read(inode)) { + error = inode_newsize_ok(inode, attr->ia_size); + if (error) + return error; + + truncate_setsize(inode, attr->ia_size); + minix_truncate(inode); + } + + setattr_copy(&nop_mnt_idmap, inode, attr); + mark_inode_dirty(inode); + return 0; +} + +const struct inode_operations minix_file_inode_operations = { + .setattr = minix_setattr, + .getattr = minix_getattr, +}; -- cgit v1.3.1