From 4bc49ae344d65cfcef738f281ac575cf73ca2fc5 Mon Sep 17 00:00:00 2001 From: Yiyang Chen Date: Sun, 16 Aug 2026 10:56:33 +0000 Subject: bpf: Check pointer type for all atomic RMW paths Atomic RMW verification records an instruction pointer type only when the current destination is PTR_TO_ARENA. A second path can therefore reach the same instruction with an ordinary pointer without comparing it against the saved arena type. The post-verification fixup uses the saved type to rewrite the instruction to BPF_PROBE_ATOMIC for every path. Record the actual destination type for all atomic RMW paths so the existing mismatch check rejects incompatible uses of one instruction. Fixes: d503a04f8bc0 ("bpf: Add support for certain atomics in bpf_arena to x86 JIT") Signed-off-by: Yiyang Chen Acked-by: Eduard Zingerman Link: https://patch.msgid.link/20260816-bpf-next-038-mixed-atomic-v1-v2-1-4644c1886dbc@mails.tsinghua.edu.cn Signed-off-by: Eduard Zingerman --- kernel/bpf/verifier.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) (limited to 'kernel') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index d17f14b35b79..93463caf5c9a 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -6739,11 +6739,9 @@ static int check_atomic_rmw(struct bpf_verifier_env *env, if (err) return err; - if (is_arena_reg(env, insn->dst_reg)) { - err = save_aux_ptr_type(env, PTR_TO_ARENA, false); - if (err) - return err; - } + err = save_aux_ptr_type(env, dst_reg->type, false); + if (err) + return err; /* Check whether we can write into the same memory. */ err = check_mem_access(env, env->insn_idx, dst_reg, argno_from_reg(insn->dst_reg), insn->off, BPF_SIZE(insn->code), BPF_WRITE, -1, true, false); -- cgit v1.2.3