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/fsel.c | 41 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 41 insertions(+) create mode 100644 arch/powerpc/math-emu/fsel.c (limited to 'arch/powerpc/math-emu/fsel.c') diff --git a/arch/powerpc/math-emu/fsel.c b/arch/powerpc/math-emu/fsel.c new file mode 100644 index 000000000..b0d15e15a --- /dev/null +++ b/arch/powerpc/math-emu/fsel.c @@ -0,0 +1,41 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include + +#include +#include +#include + +int +fsel(u32 *frD, void *frA, u32 *frB, u32 *frC) +{ + FP_DECL_D(A); + FP_DECL_EX; + +#ifdef DEBUG + printk("%s: %p %p %p %p\n", __func__, frD, frA, frB, frC); +#endif + + FP_UNPACK_DP(A, frA); + +#ifdef DEBUG + printk("A: %ld %lu %lu %ld (%ld)\n", A_s, A_f1, A_f0, A_e, A_c); + printk("B: %08x %08x\n", frB[0], frB[1]); + printk("C: %08x %08x\n", frC[0], frC[1]); +#endif + + if (A_c == FP_CLS_NAN || (A_c != FP_CLS_ZERO && A_s)) { + frD[0] = frB[0]; + frD[1] = frB[1]; + } else { + frD[0] = frC[0]; + frD[1] = frC[1]; + } + +#ifdef DEBUG + printk("D: %08x.%08x\n", frD[0], frD[1]); +#endif + + return 0; +} -- cgit v1.3.1