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/qnx4/dir.c | 81 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 81 insertions(+) create mode 100644 fs/qnx4/dir.c (limited to 'fs/qnx4/dir.c') diff --git a/fs/qnx4/dir.c b/fs/qnx4/dir.c new file mode 100644 index 000000000..a9038d231 --- /dev/null +++ b/fs/qnx4/dir.c @@ -0,0 +1,81 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * QNX4 file system, Linux implementation. + * + * Version : 0.2.1 + * + * Using parts of the xiafs filesystem. + * + * History : + * + * 28-05-1998 by Richard Frowijn : first release. + * 20-06-1998 by Frank Denis : Linux 2.1.99+ & dcache support. + */ + +#include +#include +#include "qnx4.h" + +static int qnx4_readdir(struct file *file, struct dir_context *ctx) +{ + struct inode *inode = file_inode(file); + unsigned int offset; + struct buffer_head *bh; + unsigned long blknum; + int ix, ino; + int size; + + QNX4DEBUG((KERN_INFO "qnx4_readdir:i_size = %ld\n", (long) inode->i_size)); + QNX4DEBUG((KERN_INFO "pos = %ld\n", (long) ctx->pos)); + + while (ctx->pos < inode->i_size) { + blknum = qnx4_block_map(inode, ctx->pos >> QNX4_BLOCK_SIZE_BITS); + bh = sb_bread(inode->i_sb, blknum); + if (bh == NULL) { + printk(KERN_ERR "qnx4_readdir: bread failed (%ld)\n", blknum); + return 0; + } + ix = (ctx->pos >> QNX4_DIR_ENTRY_SIZE_BITS) % QNX4_INODES_PER_BLOCK; + for (; ix < QNX4_INODES_PER_BLOCK; ix++, ctx->pos += QNX4_DIR_ENTRY_SIZE) { + union qnx4_directory_entry *de; + const char *fname; + + offset = ix * QNX4_DIR_ENTRY_SIZE; + de = (union qnx4_directory_entry *) (bh->b_data + offset); + + fname = get_entry_fname(de, &size); + if (!fname) + continue; + + if (!(de->de_status & QNX4_FILE_LINK)) { + ino = blknum * QNX4_INODES_PER_BLOCK + ix - 1; + } else { + ino = ( le32_to_cpu(de->link.dl_inode_blk) - 1 ) * + QNX4_INODES_PER_BLOCK + + de->link.dl_inode_ndx; + } + + QNX4DEBUG((KERN_INFO "qnx4_readdir:%.*s\n", size, fname)); + if (!dir_emit(ctx, fname, size, ino, DT_UNKNOWN)) { + brelse(bh); + return 0; + } + } + brelse(bh); + } + return 0; +} + +const struct file_operations qnx4_dir_operations = +{ + .llseek = generic_file_llseek, + .read = generic_read_dir, + .iterate_shared = qnx4_readdir, + .fsync = simple_fsync, + .setlease = generic_setlease, +}; + +const struct inode_operations qnx4_dir_inode_operations = +{ + .lookup = qnx4_lookup, +}; -- cgit v1.3.1