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 --- drivers/md/dm-pcache/segment.c | 61 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 61 insertions(+) create mode 100644 drivers/md/dm-pcache/segment.c (limited to 'drivers/md/dm-pcache/segment.c') diff --git a/drivers/md/dm-pcache/segment.c b/drivers/md/dm-pcache/segment.c new file mode 100644 index 000000000..7e9818701 --- /dev/null +++ b/drivers/md/dm-pcache/segment.c @@ -0,0 +1,61 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +#include + +#include "pcache_internal.h" +#include "cache_dev.h" +#include "segment.h" + +int segment_copy_to_bio(struct pcache_segment *segment, + u32 data_off, u32 data_len, struct bio *bio, u32 bio_off) +{ + struct iov_iter iter; + size_t copied; + void *src; + + iov_iter_bvec(&iter, ITER_DEST, &bio->bi_io_vec[bio->bi_iter.bi_idx], + bio_segments(bio), bio->bi_iter.bi_size); + iter.iov_offset = bio->bi_iter.bi_bvec_done; + if (bio_off) + iov_iter_advance(&iter, bio_off); + + src = segment->data + data_off; + copied = _copy_mc_to_iter(src, data_len, &iter); + if (copied != data_len) + return -EIO; + + return 0; +} + +int segment_copy_from_bio(struct pcache_segment *segment, + u32 data_off, u32 data_len, struct bio *bio, u32 bio_off) +{ + struct iov_iter iter; + size_t copied; + void *dst; + + iov_iter_bvec(&iter, ITER_SOURCE, &bio->bi_io_vec[bio->bi_iter.bi_idx], + bio_segments(bio), bio->bi_iter.bi_size); + iter.iov_offset = bio->bi_iter.bi_bvec_done; + if (bio_off) + iov_iter_advance(&iter, bio_off); + + dst = segment->data + data_off; + copied = _copy_from_iter_flushcache(dst, data_len, &iter); + if (copied != data_len) + return -EIO; + pmem_wmb(); + + return 0; +} + +void pcache_segment_init(struct pcache_cache_dev *cache_dev, struct pcache_segment *segment, + struct pcache_segment_init_options *options) +{ + segment->seg_info = options->seg_info; + segment_info_set_type(segment->seg_info, options->type); + + segment->cache_dev = cache_dev; + segment->seg_id = options->seg_id; + segment->data_size = PCACHE_SEG_SIZE - options->data_off; + segment->data = CACHE_DEV_SEGMENT(cache_dev, options->seg_id) + options->data_off; +} -- cgit v1.3.1