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/arm/lib/bswapsdi2.S | 38 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 38 insertions(+) create mode 100644 arch/arm/lib/bswapsdi2.S (limited to 'arch/arm/lib/bswapsdi2.S') diff --git a/arch/arm/lib/bswapsdi2.S b/arch/arm/lib/bswapsdi2.S new file mode 100644 index 000000000..591ba077e --- /dev/null +++ b/arch/arm/lib/bswapsdi2.S @@ -0,0 +1,38 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#include +#include + +#if __LINUX_ARM_ARCH__ >= 6 +ENTRY(__bswapsi2) + rev r0, r0 + bx lr +ENDPROC(__bswapsi2) + +ENTRY(__bswapdi2) + rev r3, r0 + rev r0, r1 + mov r1, r3 + bx lr +ENDPROC(__bswapdi2) +#else +ENTRY(__bswapsi2) + eor r3, r0, r0, ror #16 + mov r3, r3, lsr #8 + bic r3, r3, #0xff00 + eor r0, r3, r0, ror #8 + ret lr +ENDPROC(__bswapsi2) + +ENTRY(__bswapdi2) + mov ip, r1 + eor r3, ip, ip, ror #16 + eor r1, r0, r0, ror #16 + mov r1, r1, lsr #8 + mov r3, r3, lsr #8 + bic r3, r3, #0xff00 + bic r1, r1, #0xff00 + eor r1, r1, r0, ror #8 + eor r0, r3, ip, ror #8 + ret lr +ENDPROC(__bswapdi2) +#endif -- cgit v1.3.1