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 --- arch/powerpc/math-emu/stfs.c | 43 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 43 insertions(+) create mode 100644 arch/powerpc/math-emu/stfs.c (limited to 'arch/powerpc/math-emu/stfs.c') diff --git a/arch/powerpc/math-emu/stfs.c b/arch/powerpc/math-emu/stfs.c new file mode 100644 index 000000000..ddf9bbdb5 --- /dev/null +++ b/arch/powerpc/math-emu/stfs.c @@ -0,0 +1,43 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include + +#include +#include +#include +#include + +int +stfs(void *frS, void *ea) +{ + FP_DECL_D(A); + FP_DECL_S(R); + FP_DECL_EX; + float f; + +#ifdef DEBUG + printk("%s: S %p, ea %p\n", __func__, frS, ea); +#endif + + FP_UNPACK_DP(A, frS); + +#ifdef DEBUG + printk("A: %ld %lu %lu %ld (%ld)\n", A_s, A_f1, A_f0, A_e, A_c); +#endif + + FP_CONV(S, D, 1, 2, R, A); + +#ifdef DEBUG + printk("R: %ld %lu %ld (%ld)\n", R_s, R_f, R_e, R_c); +#endif + + _FP_PACK_CANONICAL(S, 1, R); + if (!FP_CUR_EXCEPTIONS || !__FPU_TRAP_P(FP_CUR_EXCEPTIONS)) { + _FP_PACK_RAW_1_P(S, &f, R); + if (copy_to_user(ea, &f, sizeof(float))) + return -EFAULT; + } + + return FP_CUR_EXCEPTIONS; +} -- cgit v1.3.1