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 877AC13F016; Tue, 27 Feb 2024 14:01:19 +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=1709042479; cv=none; b=ClNPdRKeWuLsC1zViCqVfnN6NDbVW5jpKL2K0mAvRaGiIZYVXuK92UV6gPp/3+hjMUpnN9V/bbcywI7UFZmJ8L3V+rR3i08xCMnAJtJNn3bsAqeviQG5DSfpa5RslKAyFKC3Z5w/btf+0u8TLqW9YjMUG/Ao+oUI2uP8DXluBcw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709042479; c=relaxed/simple; bh=7A12yH7fCGPugFYFIfAV432yJRSRe8sKyklQ+vjXQ7I=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=H3h8ZuB5IiCpV7RDiVhZ7tPhlnFlk96kcLythuX1Osvi5o+tw+Zh1FS3RbeTU/9ldbpvxZElH9ITLE7+18j+Z3h4EjvoUrFa83HAPVVUQRk48beahhzuvwhhbDnobG+1dY94Bkv8HE9EU9Kig+5AJjEoVKQSJseDvwYebwVxa0w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=h6zM9AKJ; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="h6zM9AKJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 146CEC433F1; Tue, 27 Feb 2024 14:01:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1709042479; bh=7A12yH7fCGPugFYFIfAV432yJRSRe8sKyklQ+vjXQ7I=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=h6zM9AKJP9nIpoX7Dw1hz0aAh7k1NpjHcS7ofqfjFKvBAwiAv0Y+26ICtW5NVepC8 dW56ujfeTA+r6OIrzKl2VEbX4e1Jgr7nDQNKbhxSiW7WSPBbVyk8DkTE2nveK7gbtz iYV8iEjsmc3pRb5muCcypqJ7e1u3SaLaZj7uY3o0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jiri Olsa , Daniel Borkmann , Yonghong Song , Thadeu Lima de Souza Cascardo Subject: [PATCH 5.15 011/245] bpf: Do cleanup in bpf_bprintf_cleanup only when needed Date: Tue, 27 Feb 2024 14:23:19 +0100 Message-ID: <20240227131615.478080020@linuxfoundation.org> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20240227131615.098467438@linuxfoundation.org> References: <20240227131615.098467438@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ 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 [cascardo: there is no bpf_trace_vprintk in 5.15] Signed-off-by: Thadeu Lima de Souza Cascardo Signed-off-by: Greg Kroah-Hartman --- include/linux/bpf.h | 2 +- kernel/bpf/helpers.c | 16 +++++++++------- kernel/trace/bpf_trace.c | 4 ++-- 3 files changed, 12 insertions(+), 10 deletions(-) --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -2299,6 +2299,6 @@ 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); #endif /* _LINUX_BPF_H */ --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -738,12 +738,14 @@ static int try_get_fmt_tmp_buf(char **tm 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(); } /* @@ -975,7 +977,7 @@ nocopy_fmt: err = 0; out: if (err) - bpf_bprintf_cleanup(); + bpf_bprintf_cleanup(data); return err; } @@ -1001,7 +1003,7 @@ BPF_CALL_5(bpf_snprintf, char *, str, u3 err = bstr_printf(str, str_size, fmt, data.bin_args); - bpf_bprintf_cleanup(); + bpf_bprintf_cleanup(&data); return err + 1; } --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -387,7 +387,7 @@ BPF_CALL_5(bpf_trace_printk, char *, fmt trace_bpf_trace_printk(buf); raw_spin_unlock_irqrestore(&trace_printk_lock, flags); - bpf_bprintf_cleanup(); + bpf_bprintf_cleanup(&data); return ret; } @@ -435,7 +435,7 @@ BPF_CALL_5(bpf_seq_printf, struct seq_fi seq_bprintf(m, fmt, data.bin_args); - bpf_bprintf_cleanup(); + bpf_bprintf_cleanup(&data); return seq_has_overflowed(m) ? -EOVERFLOW : 0; }