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/arc/lib/memcpy-700.S | 63 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 63 insertions(+) create mode 100644 arch/arc/lib/memcpy-700.S (limited to 'arch/arc/lib/memcpy-700.S') diff --git a/arch/arc/lib/memcpy-700.S b/arch/arc/lib/memcpy-700.S new file mode 100644 index 000000000..f2e239e21 --- /dev/null +++ b/arch/arc/lib/memcpy-700.S @@ -0,0 +1,63 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) + */ + +#include + +ENTRY_CFI(memcpy) + or r3,r0,r1 + asl_s r3,r3,30 + mov_s r5,r0 + brls.d r2,r3,.Lcopy_bytewise + sub.f r3,r2,1 + ld_s r12,[r1,0] + asr.f lp_count,r3,3 + bbit0.d r3,2,.Lnox4 + bmsk_s r2,r2,1 + st.ab r12,[r5,4] + ld.a r12,[r1,4] +.Lnox4: + lppnz .Lendloop + ld_s r3,[r1,4] + st.ab r12,[r5,4] + ld.a r12,[r1,8] + st.ab r3,[r5,4] +.Lendloop: + breq r2,0,.Last_store + ld r3,[r5,0] +#ifdef __LITTLE_ENDIAN__ + add3 r2,-1,r2 + ; uses long immediate + xor_s r12,r12,r3 + bmsk r12,r12,r2 + xor_s r12,r12,r3 +#else /* BIG ENDIAN */ + sub3 r2,31,r2 + ; uses long immediate + xor_s r3,r3,r12 + bmsk r3,r3,r2 + xor_s r12,r12,r3 +#endif /* ENDIAN */ +.Last_store: + j_s.d [blink] + st r12,[r5,0] + + .balign 4 +.Lcopy_bytewise: + jcs [blink] + ldb_s r12,[r1,0] + lsr.f lp_count,r3 + bhs_s .Lnox1 + stb.ab r12,[r5,1] + ldb.a r12,[r1,1] +.Lnox1: + lppnz .Lendbloop + ldb_s r3,[r1,1] + stb.ab r12,[r5,1] + ldb.a r12,[r1,2] + stb.ab r3,[r5,1] +.Lendbloop: + j_s.d [blink] + stb r12,[r5,0] +END_CFI(memcpy) -- cgit v1.3.1