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/iomap/seek.c | 100 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 100 insertions(+) create mode 100644 fs/iomap/seek.c (limited to 'fs/iomap/seek.c') diff --git a/fs/iomap/seek.c b/fs/iomap/seek.c new file mode 100644 index 000000000..6cbc587c9 --- /dev/null +++ b/fs/iomap/seek.c @@ -0,0 +1,100 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2017 Red Hat, Inc. + * Copyright (c) 2018-2021 Christoph Hellwig. + */ +#include +#include + +static int iomap_seek_hole_iter(struct iomap_iter *iter, + loff_t *hole_pos) +{ + loff_t length = iomap_length(iter); + + switch (iter->iomap.type) { + case IOMAP_UNWRITTEN: + *hole_pos = mapping_seek_hole_data(iter->inode->i_mapping, + iter->pos, iter->pos + length, SEEK_HOLE); + if (*hole_pos == iter->pos + length) + return iomap_iter_advance(iter, length); + return 0; + case IOMAP_HOLE: + *hole_pos = iter->pos; + return 0; + default: + return iomap_iter_advance(iter, length); + } +} + +loff_t +iomap_seek_hole(struct inode *inode, loff_t pos, const struct iomap_ops *ops) +{ + loff_t size = i_size_read(inode); + struct iomap_iter iter = { + .inode = inode, + .pos = pos, + .flags = IOMAP_REPORT, + }; + int ret; + + /* Nothing to be found before or beyond the end of the file. */ + if (pos < 0 || pos >= size) + return -ENXIO; + + iter.len = size - pos; + while ((ret = iomap_iter(&iter, ops)) > 0) + iter.status = iomap_seek_hole_iter(&iter, &pos); + if (ret < 0) + return ret; + if (iter.len) /* found hole before EOF */ + return pos; + return size; +} +EXPORT_SYMBOL_GPL(iomap_seek_hole); + +static int iomap_seek_data_iter(struct iomap_iter *iter, + loff_t *hole_pos) +{ + loff_t length = iomap_length(iter); + + switch (iter->iomap.type) { + case IOMAP_HOLE: + return iomap_iter_advance(iter, length); + case IOMAP_UNWRITTEN: + *hole_pos = mapping_seek_hole_data(iter->inode->i_mapping, + iter->pos, iter->pos + length, SEEK_DATA); + if (*hole_pos < 0) + return iomap_iter_advance(iter, length); + return 0; + default: + *hole_pos = iter->pos; + return 0; + } +} + +loff_t +iomap_seek_data(struct inode *inode, loff_t pos, const struct iomap_ops *ops) +{ + loff_t size = i_size_read(inode); + struct iomap_iter iter = { + .inode = inode, + .pos = pos, + .flags = IOMAP_REPORT, + }; + int ret; + + /* Nothing to be found before or beyond the end of the file. */ + if (pos < 0 || pos >= size) + return -ENXIO; + + iter.len = size - pos; + while ((ret = iomap_iter(&iter, ops)) > 0) + iter.status = iomap_seek_data_iter(&iter, &pos); + if (ret < 0) + return ret; + if (iter.len) /* found data before EOF */ + return pos; + /* We've reached the end of the file without finding data */ + return -ENXIO; +} +EXPORT_SYMBOL_GPL(iomap_seek_data); -- cgit v1.3.1