From nobody Sun Dec 14 19:31:52 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 A99BD231A3B; Wed, 21 May 2025 18:39:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747852759; cv=none; b=K/cfEUPCbYrKD71pDu7JGcELx+I8dvFwaSX4SgTrafju8V9rlzmqqXcjc8lsIsdu34w6bfXzRcEJG+kPCYQXzyiN14vuDb+an8qcDjFwKaEzZ8gO8pcOmEfTjgeDCXPf/ftWZqmDW6MFPrS95byC9OUQRzXx8X93hsD+hWfRhCY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747852759; c=relaxed/simple; bh=SBLn1mgsCy1yNEPCrv9gyDzDQdEqfOao0Sm1vEgW7PA=; h=From:To:Subject:Date:Message-ID:MIME-Version; b=DNw2Wb00XCIoPgPeOQdVjqsVeQ0ccitRAWM8l0tM68UhkpoNDxHqYfhyVx0JPPDS9QwaOdSxRz1I3+uSzLocpaJ+qrkJfnIwfwRBw4HHt8I9zw3veOIgwf3t8Jv8fPlSJT3uv/2gv/JG0c/G2/qW1L3qfH3xRp9XGNSHMGs+x/s= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=E3Yenc73; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="E3Yenc73" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DBA2AC4CEE4; Wed, 21 May 2025 18:39:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1747852758; bh=SBLn1mgsCy1yNEPCrv9gyDzDQdEqfOao0Sm1vEgW7PA=; h=From:To:Subject:Date:From; b=E3Yenc7324pISYWoa4gqYevKb7WyXAR4Sqja93qV0uAesVQUVzrh7qJPfqb+0W7kI V/VJ8bErdlbIyUGaq+2yHgG9ahz2fwykiCcJotU9RF8mPeHsPcwIDBCcohVTYiMQlU ZMgTnDQ3ZmKQYGpEjBN0FDqs2cJeYZwZVQR4wDkLR70Ls7t3wftBqb5mBNLKnZX5nW Eafb8Dk4csYUPwp7R1EALiVWOraeHIkMv6qXb1Q4Kq9niyPh19UW1zk7j01GMCM0dE hU/eB/k4feF0qErLAV4vysR0X+ufke+VFTZnZqnhLuapCisYZRSIccHoIM9N2MHdS1 pN9CYluQOlRgQ== From: Puranjay Mohan To: Alexei Starovoitov , Daniel Borkmann , John Fastabend , Andrii Nakryiko , Martin KaFai Lau , Eduard Zingerman , Song Liu , Yonghong Song , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , bpf@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH bpf] bpf: verifier: support BPF_LOAD_ACQ in insn_def_regno() Date: Wed, 21 May 2025 18:39:09 +0000 Message-ID: <20250521183911.21781-1-puranjay@kernel.org> X-Mailer: git-send-email 2.47.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" insn_def_regno() currently returns -1 for a BPF_LOAD_ACQ which is incorrect as BPF_LOAD_ACQ loads a value from (src_reg + off) into the dst_reg. This was uncovered by syzkaller while fuzzing on arm32 architecture where this function was being called by opt_subreg_zext_lo32_rnd_hi32() and the warning inside this function was triggered because the BPF_LOAD_ACQ instruction can read 32 bit values so it needs to be zero-extended on some archs (eg. arm32) but the destination register (to be zero-extended) returned by insn_def_regno() was invalid (-1). Fixes: 880442305a39 ("bpf: Introduce load-acquire and store-release instruc= tions") Reported-by: syzbot+0ef84a7bdf5301d4cbec@syzkaller.appspotmail.com Closes: https://lore.kernel.org/bpf/682dd10b.a00a0220.29bc26.028e.GAE@googl= e.com/T/#m1457e14da8cf6c1d9703b446c224407bca758f5c Signed-off-by: Puranjay Mohan --- kernel/bpf/verifier.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 54c6953a8b84..9aa67e46cb8b 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -3643,6 +3643,9 @@ static bool is_reg64(struct bpf_verifier_env *env, st= ruct bpf_insn *insn, /* Return the regno defined by the insn, or -1. */ static int insn_def_regno(const struct bpf_insn *insn) { + if (is_atomic_load_insn(insn)) + return insn->dst_reg; + switch (BPF_CLASS(insn->code)) { case BPF_JMP: case BPF_JMP32: --=20 2.47.1