From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from fanzine2.igalia.com (fanzine2.igalia.com [213.97.179.56]) (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 0DD826A023 for ; Sat, 17 Feb 2024 12:13:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.97.179.56 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708172027; cv=none; b=T95K5KfPCH5jDxPzXh8YrYhKowrJeYpvxoY/qGI5QYXP8iPKw4PACrokul8lGtw158dW/5d1suIhgD6hCIf96A3nIO/YK0/esS7F6optNOhZFACq6BxxmW+59oOxZ9ordCnZ114wRgguJ4JhC3ZZ0uGaZrXrwfY3GhidK3306NA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708172027; c=relaxed/simple; bh=bUHKGl73hmGWftah8yabQNN6Hwu/83ug2T1nexfoe0c=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=hzQsvsvtVsmSSjWjEVbMjSv3Wauno44JmRMN1h0h0JB2jYEg8S0AB6/boRwxIaZ+GIBLq2m6wRUXd9rliuZ5NOeiyihjSWrbs/Cp6AcBe+qaAsGpZgCUIIY4XItxP6JLTLZZNZ/yrV+Wp7SeJmX/sFwGQWNBeQ0ZkZ/RFOsJzgk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=igalia.com; spf=pass smtp.mailfrom=igalia.com; dkim=pass (2048-bit key) header.d=igalia.com header.i=@igalia.com header.b=kqwbEBQU; arc=none smtp.client-ip=213.97.179.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=igalia.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=igalia.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=igalia.com header.i=@igalia.com header.b="kqwbEBQU" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Content-Transfer-Encoding:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To:Content-Type:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=ovarhB65lp1Wy61UDe6WEjO0J/Y5CD9FOsflZN9D4qA=; b=kqwbEBQU5gAKZr7PIbbZBo2WCd sWpm56tiYx5QL29I/SCMfY//Xw+mI2rr5udTQVm7O0ysVvPuPOSxceJJ/IL94+3YTjL8O8J9Qs5OD NINlBFetF3A394iPM2Bx5ldVmqoYCyNP8UxZmANSF65rM9amHNXegTE2g91gwlmoasumvpGZFRX4F MNSbkowFTq2VUL7evnMBn/URoTVAjtsT+SSG+u8U3A7y0kbX2HwIqJVJUjsSAwqYtfAGAO9uY1YUo rlVL8ol3JK5nCanV/UnGysiy+tXtwN7nPOuW2yBWVTRNK9wTVPvTzlV9rQK94+66gChCTCNKmpEXq XdaSkV8A==; Received: from 179-125-79-204-dinamico.pombonet.net.br ([179.125.79.204] helo=quatroqueijos.lan) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim) id 1rbJZW-000joD-2U; Sat, 17 Feb 2024 13:13:34 +0100 From: Thadeu Lima de Souza Cascardo To: stable@vger.kernel.org Cc: cascardo@igalia.com, jolsa@kernel.org, daniel@iogearbox.net, yhs@fb.com Subject: [PATCH 6.1 2/3] bpf: Do cleanup in bpf_bprintf_cleanup only when needed Date: Sat, 17 Feb 2024 09:13:16 -0300 Message-Id: <20240217121321.2045993-3-cascardo@igalia.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240217121321.2045993-1-cascardo@igalia.com> References: <20240217121321.2045993-1-cascardo@igalia.com> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Jiri Olsa commit f19a4050455aad847fb93f18dc1fe502eb60f989 upstream. Currently we always cleanup/decrement bpf_bprintf_nest_level variable in bpf_bprintf_cleanup if it's > 0. There's possible scenario where this could cause a problem, when bpf_bprintf_prepare does not get bin_args buffer (because num_args is 0) and following bpf_bprintf_cleanup call decrements bpf_bprintf_nest_level variable, like: in task context: bpf_bprintf_prepare(num_args != 0) increments 'bpf_bprintf_nest_level = 1' -> first irq : bpf_bprintf_prepare(num_args == 0) bpf_bprintf_cleanup decrements 'bpf_bprintf_nest_level = 0' -> second irq: bpf_bprintf_prepare(num_args != 0) bpf_bprintf_nest_level = 1 gets same buffer as task context above Adding check to bpf_bprintf_cleanup and doing the real cleanup only if we got bin_args data in the first place. Signed-off-by: Jiri Olsa Signed-off-by: Daniel Borkmann Acked-by: Yonghong Song Link: https://lore.kernel.org/bpf/20221215214430.1336195-3-jolsa@kernel.org Signed-off-by: Thadeu Lima de Souza Cascardo --- include/linux/bpf.h | 2 +- kernel/bpf/helpers.c | 16 +++++++++------- kernel/trace/bpf_trace.c | 6 +++--- 3 files changed, 13 insertions(+), 11 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 0e4fb16cd5c1..bc4e6969899a 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -2747,7 +2747,7 @@ struct bpf_bprintf_data { int bpf_bprintf_prepare(char *fmt, u32 fmt_size, const u64 *raw_args, u32 num_args, struct bpf_bprintf_data *data); -void bpf_bprintf_cleanup(void); +void bpf_bprintf_cleanup(struct bpf_bprintf_data *data); /* the implementation of the opaque uapi struct bpf_dynptr */ struct bpf_dynptr_kern { diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index 42141d59e9c6..64f41f58b37b 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -781,12 +781,14 @@ static int try_get_fmt_tmp_buf(char **tmp_buf) return 0; } -void bpf_bprintf_cleanup(void) +void bpf_bprintf_cleanup(struct bpf_bprintf_data *data) { - if (this_cpu_read(bpf_bprintf_nest_level)) { - this_cpu_dec(bpf_bprintf_nest_level); - preempt_enable(); - } + if (!data->bin_args) + return; + if (WARN_ON_ONCE(this_cpu_read(bpf_bprintf_nest_level) == 0)) + return; + this_cpu_dec(bpf_bprintf_nest_level); + preempt_enable(); } /* @@ -1018,7 +1020,7 @@ int bpf_bprintf_prepare(char *fmt, u32 fmt_size, const u64 *raw_args, err = 0; out: if (err) - bpf_bprintf_cleanup(); + bpf_bprintf_cleanup(data); return err; } @@ -1044,7 +1046,7 @@ BPF_CALL_5(bpf_snprintf, char *, str, u32, str_size, char *, fmt, err = bstr_printf(str, str_size, fmt, data.bin_args); - bpf_bprintf_cleanup(); + bpf_bprintf_cleanup(&data); return err + 1; } diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index bbf44095999f..263a54d0d9ee 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -395,7 +395,7 @@ BPF_CALL_5(bpf_trace_printk, char *, fmt, u32, fmt_size, u64, arg1, trace_bpf_trace_printk(buf); raw_spin_unlock_irqrestore(&trace_printk_lock, flags); - bpf_bprintf_cleanup(); + bpf_bprintf_cleanup(&data); return ret; } @@ -453,7 +453,7 @@ BPF_CALL_4(bpf_trace_vprintk, char *, fmt, u32, fmt_size, const void *, args, trace_bpf_trace_printk(buf); raw_spin_unlock_irqrestore(&trace_printk_lock, flags); - bpf_bprintf_cleanup(); + bpf_bprintf_cleanup(&data); return ret; } @@ -493,7 +493,7 @@ BPF_CALL_5(bpf_seq_printf, struct seq_file *, m, char *, fmt, u32, fmt_size, seq_bprintf(m, fmt, data.bin_args); - bpf_bprintf_cleanup(); + bpf_bprintf_cleanup(&data); return seq_has_overflowed(m) ? -EOVERFLOW : 0; } -- 2.34.1