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 A7B90749A for ; Thu, 12 Jan 2023 14:05:54 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 23840C433D2; Thu, 12 Jan 2023 14:05:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1673532354; bh=amqTdM9XMNnHKete7CvX/sBJxSkCGR5FUoOd94KIqcw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dDrUbDoImAGi3wn07jEaaa5aNdAEhRT9ethmAKiFcOAHuuE5nFB5bk+ddLwkWKHd5 D3vKQo9uAJISdJiT7zzyCUhrwds4xDx9OzaRGjbCkNV6Uz0eQ7b6yp3qRcqzZK+i77 YvTFMkDSgVIjOcnKYv/JuAH6AkMToPYTSw6ahznE= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Kumar Kartikeya Dwivedi , Alexei Starovoitov , Sasha Levin Subject: [PATCH 5.10 133/783] bpf: Fix slot type check in check_stack_write_var_off Date: Thu, 12 Jan 2023 14:47:29 +0100 Message-Id: <20230112135530.484850348@linuxfoundation.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230112135524.143670746@linuxfoundation.org> References: <20230112135524.143670746@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Kumar Kartikeya Dwivedi [ Upstream commit f5e477a861e4a20d8a1c5f7a245f3a3c3c376b03 ] For the case where allow_ptr_leaks is false, code is checking whether slot type is STACK_INVALID and STACK_SPILL and rejecting other cases. This is a consequence of incorrectly checking for register type instead of the slot type (NOT_INIT and SCALAR_VALUE respectively). Fix the check. Fixes: 01f810ace9ed ("bpf: Allow variable-offset stack access") Signed-off-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20221103191013.1236066-5-memxor@gmail.com Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin --- kernel/bpf/verifier.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 50364031eb4d..4d62822f5502 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2439,14 +2439,17 @@ static int check_stack_write_var_off(struct bpf_verifier_env *env, spi = slot / BPF_REG_SIZE; stype = &state->stack[spi].slot_type[slot % BPF_REG_SIZE]; - if (!env->allow_ptr_leaks - && *stype != NOT_INIT - && *stype != SCALAR_VALUE) { - /* Reject the write if there's are spilled pointers in - * range. If we didn't reject here, the ptr status - * would be erased below (even though not all slots are - * actually overwritten), possibly opening the door to - * leaks. + if (!env->allow_ptr_leaks && *stype != STACK_MISC && *stype != STACK_ZERO) { + /* Reject the write if range we may write to has not + * been initialized beforehand. If we didn't reject + * here, the ptr status would be erased below (even + * though not all slots are actually overwritten), + * possibly opening the door to leaks. + * + * We do however catch STACK_INVALID case below, and + * only allow reading possibly uninitialized memory + * later for CAP_PERFMON, as the write may not happen to + * that slot. */ verbose(env, "spilled ptr in range of var-offset stack write; insn %d, ptr off: %d", insn_idx, i); -- 2.35.1