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/coda/symlink.c | 40 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 40 insertions(+) create mode 100644 fs/coda/symlink.c (limited to 'fs/coda/symlink.c') diff --git a/fs/coda/symlink.c b/fs/coda/symlink.c new file mode 100644 index 000000000..40f84d014 --- /dev/null +++ b/fs/coda/symlink.c @@ -0,0 +1,40 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Symlink inode operations for Coda filesystem + * Original version: (C) 1996 P. Braam and M. Callahan + * Rewritten for Linux 2.1. (C) 1997 Carnegie Mellon University + * + * Carnegie Mellon encourages users to contribute improvements to + * the Coda project. Contact Peter Braam (coda@cs.cmu.edu). + */ + +#include +#include +#include +#include +#include +#include +#include + +#include +#include "coda_psdev.h" +#include "coda_linux.h" + +static int coda_symlink_filler(struct file *file, struct folio *folio) +{ + struct inode *inode = folio->mapping->host; + int error; + struct coda_inode_info *cii; + unsigned int len = PAGE_SIZE; + char *p = folio_address(folio); + + cii = ITOC(inode); + + error = venus_readlink(inode->i_sb, &cii->c_fid, p, &len); + folio_end_read(folio, error == 0); + return error; +} + +const struct address_space_operations coda_symlink_aops = { + .read_folio = coda_symlink_filler, +}; -- cgit v1.3.1