From mboxrd@z Thu Jan 1 00:00:00 1970 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 2565118B11 for ; Mon, 9 Oct 2023 13:10:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="TlMXE3JX" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 91F18C433CB; Mon, 9 Oct 2023 13:10:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1696857040; bh=mQr9Dl0QfRLNQbRSBrylobpMdR9t8dfyoSaB4f2EzQA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=TlMXE3JXqDoN3/N2GF09npeetEiFAvr6vVElrwAZkBmBWP3dZjLlvlGBBpMvin2PL bhDwuFXmiPPFDrmKH/HYepYELTXvRSrjoMhNgt84DCMrwmbeXNEbCJGFU0a4B1Smv0 8r1QCGBz2Z9n9TWbsHzDKySA/dxHN/Hc/6zWOjPs= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Chris Mason , Andrii Nakryiko , Alexei Starovoitov , Sasha Levin Subject: [PATCH 6.5 076/163] bpf: unconditionally reset backtrack_state masks on global func exit Date: Mon, 9 Oct 2023 15:00:40 +0200 Message-ID: <20231009130126.155031003@linuxfoundation.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20231009130124.021290599@linuxfoundation.org> References: <20231009130124.021290599@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.5-stable review patch. If anyone has any objections, please let me know. ------------------ From: Andrii Nakryiko [ Upstream commit 81335f90e8a88b81932df011105c46e708744f44 ] In mark_chain_precision() logic, when we reach the entry to a global func, it is expected that R1-R5 might be still requested to be marked precise. This would correspond to some integer input arguments being tracked as precise. This is all expected and handled as a special case. What's not expected is that we'll leave backtrack_state structure with some register bits set. This is because for subsequent precision propagations backtrack_state is reused without clearing masks, as all code paths are carefully written in a way to leave empty backtrack_state with zeroed out masks, for speed. The fix is trivial, we always clear register bit in the register mask, and then, optionally, set reg->precise if register is SCALAR_VALUE type. Reported-by: Chris Mason Fixes: be2ef8161572 ("bpf: allow precision tracking for programs with subprogs") Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20230918210110.2241458-1-andrii@kernel.org Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin --- kernel/bpf/verifier.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 9cdba4ce23d2b..93fd32f2957b7 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -4039,11 +4039,9 @@ static int __mark_chain_precision(struct bpf_verifier_env *env, int regno) bitmap_from_u64(mask, bt_reg_mask(bt)); for_each_set_bit(i, mask, 32) { reg = &st->frame[0]->regs[i]; - if (reg->type != SCALAR_VALUE) { - bt_clear_reg(bt, i); - continue; - } - reg->precise = true; + bt_clear_reg(bt, i); + if (reg->type == SCALAR_VALUE) + reg->precise = true; } return 0; } -- 2.40.1