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 --- scripts/module.lds.S | 68 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 68 insertions(+) create mode 100644 scripts/module.lds.S (limited to 'scripts/module.lds.S') diff --git a/scripts/module.lds.S b/scripts/module.lds.S new file mode 100644 index 000000000..b62683061 --- /dev/null +++ b/scripts/module.lds.S @@ -0,0 +1,68 @@ +/* + * Common module linker script, always used when linking a module. + * Archs are free to supply their own linker scripts. ld will + * combine them automatically. + */ +#ifdef CONFIG_UNWIND_TABLES +#define DISCARD_EH_FRAME +#else +#define DISCARD_EH_FRAME *(.eh_frame) +#endif + +#include + +SECTIONS { + /DISCARD/ : { + *(.discard) + *(.discard.*) + *(.export_symbol) + *(.no_trim_symbol) + } + + __ksymtab 0 : ALIGN(8) { *(SORT(___ksymtab+*)) } + __kcrctab 0 : ALIGN(4) { *(SORT(___kcrctab+*)) } + __kflagstab 0 : ALIGN(1) { *(SORT(___kflagstab+*)) } + + .ctors 0 : ALIGN(8) { *(SORT(.ctors.*)) *(.ctors) } + .init_array 0 : ALIGN(8) { *(SORT(.init_array.*)) *(.init_array) } + + .altinstructions 0 : ALIGN(8) { KEEP(*(.altinstructions)) } + __bug_table 0 : ALIGN(8) { KEEP(*(__bug_table)) } + __jump_table 0 : ALIGN(8) { KEEP(*(__jump_table)) } + __ex_table 0 : ALIGN(4) { KEEP(*(__ex_table)) } + + __patchable_function_entries 0 : { *(__patchable_function_entries) } + + .init.klp_funcs 0 : ALIGN(8) { KEEP(*(.init.klp_funcs)) } + .init.klp_objects 0 : ALIGN(8) { KEEP(*(.init.klp_objects)) } + +#ifdef CONFIG_ARCH_USES_CFI_TRAPS + __kcfi_traps 0 : { KEEP(*(.kcfi_traps)) } +#endif + +#ifndef CONFIG_ARCH_WANTS_MODULES_TEXT_SECTIONS + .text 0 : { + *(.text .text.[0-9a-zA-Z_]*) + } +#endif + + .bss 0 : { + *(.bss .bss.[0-9a-zA-Z_]*) + *(.bss..L*) + } + + .data 0 : { + *(.data .data.[0-9a-zA-Z_]*) + *(.data..L*) + } + + .rodata 0 : { + *(.rodata .rodata.[0-9a-zA-Z_]*) + *(.rodata..L*) + } + + MOD_SEPARATE_CODETAG_SECTIONS() +} + +/* bring in arch-specific sections */ +#include -- cgit v1.3.1