From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-181.mta0.migadu.com (out-181.mta0.migadu.com [91.218.175.181]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 210543F8ED3 for ; Fri, 26 Jun 2026 15:44:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.181 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782488657; cv=none; b=ClKxr0QTXu7MVtRjEhCIk2G/i5SaSGtoYI/NpuI/KObGajGLmGDu/IOW5I7WtJ2DlYZ5Zr+hsIm2Ggvc1EAYgWUgs72kZBe31Wan+ab+acgHz6dN+HreVFdHcRFTR6HUv4A1zXpV7VpjrG8mgdHzYcWSL4y3OIL7eHsOdoL86HU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782488657; c=relaxed/simple; bh=LFJI83/WYpHfuRc1m3m73OyE0zcpWX/q8/bQyd/m6lQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=h1yRw2bH+9n/VwPawFQ8WRjJ3MhcqhH1CDa6lucu6uyyhfAITG80WcAbQFhLBAHPLDdomfeHlZaIokSl3+SoxSAITYnq9LnmOMFND3Y3yOtdtuOddsQvShCa2Z4JzUijXbcu8EA3FAByDoPeEf2jY9aRTNpTrWVpgBO+/EfSc7o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=PtgCOI24; arc=none smtp.client-ip=91.218.175.181 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="PtgCOI24" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1782488651; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=+7NjT/bLMzyhjKZ36rht9UI2veslGOj1wDwmks47Yxg=; b=PtgCOI248GDf4DNl95akD02zT2MvTD+T8ZwkqBrxawqhOUMtAslMQu1djDMYZdgu29dhoS B5dMzk8gCaF5NIzHg3Tk60mLKkqTlMQEVVAfja6p/NzOw/GdvL93fnDXc+XLq8auDRo+bK cBc/QtfIqXaUAb7SaCgOG5xl6I67at4= From: Leon Hwang To: bpf@vger.kernel.org Cc: Alexei Starovoitov , Daniel Borkmann , John Fastabend , Andrii Nakryiko , Eduard Zingerman , Kumar Kartikeya Dwivedi , Martin KaFai Lau , Song Liu , Yonghong Song , Jiri Olsa , Emil Tsalapatis , Andrew Morton , Shuah Khan , Puranjay Mohan , Anton Protopopov , linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, Leon Hwang Subject: [RFC PATCH bpf 2/6] bpf: Disallow interpreter fallback for arena insn Date: Fri, 26 Jun 2026 23:43:26 +0800 Message-ID: <20260626154330.33619-3-leon.hwang@linux.dev> In-Reply-To: <20260626154330.33619-1-leon.hwang@linux.dev> References: <20260626154330.33619-1-leon.hwang@linux.dev> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT The interpreter does not recognize the arena ST/LDX/STX insns. Thereafter, it would hit the BUG_ON() in ___bpf_prog_run() at run time. [ 2.579196] BPF interpreter: unknown opcode a2 (imm: 0x0) [ 2.579998] ------------[ cut here ]------------ [ 2.580652] kernel BUG at kernel/bpf/core.c:2349! [ 2.581314] Oops: invalid opcode: 0000 [#1] SMP PTI On the fallback path from JIT in __bpf_prog_select_runtime(), reject the BPF_PROBE_MEM32/BPF_PROBE_MEM32SX insn to avoid the BUG. Fixes: 2fe99eb0ccf2 ("bpf: Add x86-64 JIT support for PROBE_MEM32 pseudo instructions.") Fixes: a91ae3c89311 ("bpf, x86: Add support for signed arena loads") Signed-off-by: Leon Hwang --- kernel/bpf/core.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index e92eb8b7f945..37b2fac22aa2 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -2613,6 +2613,22 @@ static bool bpf_insn_requires_jit(struct bpf_insn *insn) if (insn_is_cast_user(insn)) return true; + switch (BPF_CLASS(insn->code)) { + case BPF_ST: + case BPF_LDX: + case BPF_STX: + /* arena ST/LDX/STX insns */ + if (BPF_MODE(insn->code) == BPF_PROBE_MEM32) + return true; + if (BPF_MODE(insn->code) == BPF_PROBE_MEM32SX && + BPF_CLASS(insn->code) == BPF_LDX && + BPF_SIZE(insn->code) != BPF_DW) + return true; + break; + default: + return false; + } + return false; } -- 2.54.0