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/isofs/namei.c | 167 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 167 insertions(+) create mode 100644 fs/isofs/namei.c (limited to 'fs/isofs/namei.c') diff --git a/fs/isofs/namei.c b/fs/isofs/namei.c new file mode 100644 index 000000000..3ace3d6a5 --- /dev/null +++ b/fs/isofs/namei.c @@ -0,0 +1,167 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * linux/fs/isofs/namei.c + * + * (C) 1992 Eric Youngdale Modified for ISO 9660 filesystem. + * + * (C) 1991 Linus Torvalds - minix filesystem + */ + +#include +#include "isofs.h" + +static int +isofs_cmp(struct dentry *dentry, const char *compare, int dlen) +{ + if (likely(!dentry->d_op)) + return dentry->d_name.len != dlen || memcmp(dentry->d_name.name, compare, dlen); + return dentry->d_op->d_compare(NULL, dentry->d_name.len, dentry->d_name.name, + &QSTR_LEN(compare, dlen)); +} + +/* + * isofs_find_entry() + * + * finds an entry in the specified directory with the wanted name. It + * returns the inode number of the found entry, or 0 on error. + */ +static unsigned long +isofs_find_entry(struct inode *dir, struct dentry *dentry, + unsigned long *block_rv, unsigned long *offset_rv, + char *tmpname, struct iso_directory_record *tmpde) +{ + unsigned long bufsize = ISOFS_BUFFER_SIZE(dir); + unsigned char bufbits = ISOFS_BUFFER_BITS(dir); + unsigned long block, f_pos, offset, block_saved, offset_saved; + struct buffer_head *bh = NULL; + struct isofs_sb_info *sbi = ISOFS_SB(dir->i_sb); + + if (!ISOFS_I(dir)->i_first_extent) + return 0; + + f_pos = 0; + offset = 0; + block = 0; + + while (f_pos < dir->i_size) { + struct iso_directory_record *de; + int de_len, match, i, dlen; + char *dpnt; + + if (!bh) { + bh = isofs_bread(dir, block); + if (!bh) + return 0; + } + + de = (struct iso_directory_record *) (bh->b_data + offset); + + de_len = *(unsigned char *) de; + if (!de_len) { + brelse(bh); + bh = NULL; + f_pos = (f_pos + ISOFS_BLOCK_SIZE) & ~(ISOFS_BLOCK_SIZE - 1); + block = f_pos >> bufbits; + offset = 0; + continue; + } + + block_saved = bh->b_blocknr; + offset_saved = offset; + offset += de_len; + f_pos += de_len; + + /* Make sure we have a full directory entry */ + if (offset >= bufsize) { + int slop = bufsize - offset + de_len; + memcpy(tmpde, de, slop); + offset &= bufsize - 1; + block++; + brelse(bh); + bh = NULL; + if (offset) { + bh = isofs_bread(dir, block); + if (!bh) + return 0; + memcpy((void *) tmpde + slop, bh->b_data, offset); + } + de = tmpde; + } + + dlen = de->name_len[0]; + dpnt = de->name; + /* Basic sanity check, whether name doesn't exceed dir entry */ + if (de_len < dlen + sizeof(struct iso_directory_record)) { + printk(KERN_NOTICE "iso9660: Corrupted directory entry" + " in block %lu of inode %llu\n", block, + dir->i_ino); + brelse(bh); + return 0; + } + + if (sbi->s_rock && + ((i = get_rock_ridge_filename(de, tmpname, dir)))) { + dlen = i; /* possibly -1 */ + dpnt = tmpname; +#ifdef CONFIG_JOLIET + } else if (sbi->s_joliet_level) { + dlen = get_joliet_filename(de, tmpname, dir); + dpnt = tmpname; +#endif + } else if (sbi->s_mapping == 'a') { + dlen = get_acorn_filename(de, tmpname, dir); + dpnt = tmpname; + } else if (sbi->s_mapping == 'n') { + dlen = isofs_name_translate(de, tmpname, dir); + dpnt = tmpname; + } + + /* + * Skip hidden or associated files unless hide or showassoc, + * respectively, is set + */ + match = 0; + if (dlen > 0 && + (!sbi->s_hide || + (!(de->flags[-sbi->s_high_sierra] & 1))) && + (sbi->s_showassoc || + (!(de->flags[-sbi->s_high_sierra] & 4)))) { + if (dpnt && (dlen > 1 || dpnt[0] > 1)) + match = (isofs_cmp(dentry, dpnt, dlen) == 0); + } + if (match) { + isofs_normalize_block_and_offset(de, + &block_saved, + &offset_saved); + *block_rv = block_saved; + *offset_rv = offset_saved; + brelse(bh); + return 1; + } + } + brelse(bh); + return 0; +} + +struct dentry *isofs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags) +{ + int found; + unsigned long block; + unsigned long offset; + struct inode *inode; + struct page *page; + + page = alloc_page(GFP_USER); + if (!page) + return ERR_PTR(-ENOMEM); + + found = isofs_find_entry(dir, dentry, + &block, &offset, + page_address(page), + 1024 + page_address(page)); + __free_page(page); + + inode = found ? isofs_iget(dir->i_sb, block, offset) : NULL; + + return d_splice_alias(inode, dentry); +} -- cgit v1.3.1