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 --- lib/iommu-helper.c | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) create mode 100644 lib/iommu-helper.c (limited to 'lib/iommu-helper.c') diff --git a/lib/iommu-helper.c b/lib/iommu-helper.c new file mode 100644 index 000000000..92a9f243c --- /dev/null +++ b/lib/iommu-helper.c @@ -0,0 +1,29 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * IOMMU helper functions for the free area management + */ + +#include +#include + +unsigned long iommu_area_alloc(unsigned long *map, unsigned long size, + unsigned long start, unsigned int nr, + unsigned long shift, unsigned long boundary_size, + unsigned long align_mask) +{ + unsigned long index; + + /* We don't want the last of the limit */ + size -= 1; +again: + index = bitmap_find_next_zero_area(map, size, start, nr, align_mask); + if (index < size) { + if (iommu_is_span_boundary(index, nr, shift, boundary_size)) { + start = ALIGN(shift + index, boundary_size) - shift; + goto again; + } + bitmap_set(map, index, nr); + return index; + } + return -1; +} -- cgit v1.3.1