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/boot/epapr.c | 63 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 63 insertions(+) create mode 100644 arch/powerpc/boot/epapr.c (limited to 'arch/powerpc/boot/epapr.c') diff --git a/arch/powerpc/boot/epapr.c b/arch/powerpc/boot/epapr.c new file mode 100644 index 000000000..7c5b26ade --- /dev/null +++ b/arch/powerpc/boot/epapr.c @@ -0,0 +1,63 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Bootwrapper for ePAPR compliant firmwares + * + * Copyright 2010 David Gibson , IBM Corporation. + * + * Based on earlier bootwrappers by: + * (c) Benjamin Herrenschmidt , IBM Corp,\ + * and + * Scott Wood + * Copyright (c) 2007 Freescale Semiconductor, Inc. + */ + +#include "ops.h" +#include "stdio.h" +#include "io.h" +#include + +BSS_STACK(4096); + +#define EPAPR_SMAGIC 0x65504150 +#define EPAPR_EMAGIC 0x45504150 + +static unsigned epapr_magic; +static unsigned long ima_size; +static unsigned long fdt_addr; + +static void platform_fixups(void) +{ + if ((epapr_magic != EPAPR_EMAGIC) + && (epapr_magic != EPAPR_SMAGIC)) + fatal("r6 contained 0x%08x instead of ePAPR magic number\n", + epapr_magic); + + if (ima_size < (unsigned long)_end) + printf("WARNING: Image loaded outside IMA!" + " (_end=%p, ima_size=0x%lx)\n", _end, ima_size); + if (ima_size < fdt_addr) + printf("WARNING: Device tree address is outside IMA!" + "(fdt_addr=0x%lx, ima_size=0x%lx)\n", fdt_addr, + ima_size); + if (ima_size < fdt_addr + fdt_totalsize((void *)fdt_addr)) + printf("WARNING: Device tree extends outside IMA!" + " (fdt_addr=0x%lx, size=0x%x, ima_size=0x%lx\n", + fdt_addr, fdt_totalsize((void *)fdt_addr), ima_size); +} + +void epapr_platform_init(unsigned long r3, unsigned long r4, unsigned long r5, + unsigned long r6, unsigned long r7) +{ + epapr_magic = r6; + ima_size = r7; + fdt_addr = r3; + + /* FIXME: we should process reserve entries */ + + simple_alloc_init(_end, ima_size - (unsigned long)_end, 32, 64); + + fdt_init((void *)fdt_addr); + + serial_console_init(); + platform_ops.fixups = platform_fixups; +} -- cgit v1.3.1