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 2EF60AD23; Sat, 19 Jul 2025 01:17:05 +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=1752887826; cv=none; b=RUnqJnuARgVa/n9Wfiz5fh/1bFgZnpEftMo7aUMinozs9k44bXviKTg7WaCkiikY+1Om7XkdZQFphhrEA67nIpms4umodYLobBY4jmlU2iiojvRANYmtC81ILIOEnGSFeasLwaFtu/ngUf4IvFkTj3a+q5dbfN2NrzLpl3pEalU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752887826; c=relaxed/simple; bh=FPWiPcjYSntguei1vjfZ6WAkudlepH1LgXSxbOmd/q0=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=eb7KUIGcK08jLRA+1jhySyCJn6lVaKKB/Vm1YWFR4GXrbi60NllHDgoaolNx48sYphoyLH1M8VZQX7FDOkIwZPSqWQmFKpuH0AmPVPbg1lw2U1OJOIb9ddL2yWMah4Lh8azeVc9BuCZmIMkeAsYbZeE4PJj38GYGU1s+lfUcdvY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=lvL54+0o; 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="lvL54+0o" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4C812C4CEEB; Sat, 19 Jul 2025 01:17:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1752887825; bh=FPWiPcjYSntguei1vjfZ6WAkudlepH1LgXSxbOmd/q0=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=lvL54+0oybb/4AfrH/Uc9gVtF1zi9VLicG/hkBWxbjHYh4nJEM2RIuajYWB008ZAv lFkV/028zFCxQiaMeJ23pc2XdWt5wJZrVqrvjVNM9ORBJ0CqtgbVxqb0iZpySuanAp aRqlsh+c7YNACM69GPd2zE72bdVsdfRlICe38oxAytFN6q10kLvCYeu45Ld9XqF67v S97RS3N8FWuEUZ5C0BVssNeHFV3uQ1phSmVg41x/X9NxO+/awsINQFatn60fZeDSOF xIqR+GzcJ7tIlBJ7NoVXuniMY8RtrEBElb+lMBGNhy/TbOOLSwiP0vAxLHpZ3JciL/ Z7Z232V2LlFEQ== Date: Sat, 19 Jul 2025 10:17:01 +0900 From: Masami Hiramatsu (Google) To: Steven Rostedt Cc: Mathieu Desnoyers , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Subject: Re: [PATCH 3/5] tracing: kprobe-event: Allocate string buffers from heap Message-Id: <20250719101701.0df8cde9709bdd9f0075c82a@kernel.org> In-Reply-To: <20250718134627.5d483ca4@batman.local.home> References: <175283843771.343578.8524137568048302760.stgit@devnote2> <175283846936.343578.3747359008449354291.stgit@devnote2> <20250718134627.5d483ca4@batman.local.home> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Fri, 18 Jul 2025 13:46:27 -0400 Steven Rostedt wrote: > On Fri, 18 Jul 2025 20:34:29 +0900 > "Masami Hiramatsu (Google)" wrote: > > > From: Masami Hiramatsu (Google) > > > > Allocate temporary string buffers for parsing kprobe-events > > from heap instead of stack. > > > > Signed-off-by: Masami Hiramatsu (Google) > > --- > > kernel/trace/trace_kprobe.c | 39 +++++++++++++++++++++++++-------------- > > 1 file changed, 25 insertions(+), 14 deletions(-) > > > > diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c > > index 15d7a381a128..793af6000f16 100644 > > --- a/kernel/trace/trace_kprobe.c > > +++ b/kernel/trace/trace_kprobe.c > > @@ -861,20 +861,20 @@ static int trace_kprobe_create_internal(int argc, const char *argv[], > > * FETCHARG:TYPE : use TYPE instead of unsigned long. > > */ > > struct trace_kprobe *tk __free(free_trace_kprobe) = NULL; > > + const char *event = NULL, *group = KPROBE_EVENT_SYSTEM; > > + const char **new_argv __free(kfree) = NULL; > > int i, len, new_argc = 0, ret = 0; > > - bool is_return = false; > > char *symbol __free(kfree) = NULL; > > - char *tmp = NULL; > > - const char **new_argv __free(kfree) = NULL; > > - const char *event = NULL, *group = KPROBE_EVENT_SYSTEM; > > + char *ebuf __free(kfree) = NULL; > > + char *gbuf __free(kfree) = NULL; > > + char *abuf __free(kfree) = NULL; > > + char *dbuf __free(kfree) = NULL; > > enum probe_print_type ptype; > > + bool is_return = false; > > int maxactive = 0; > > - long offset = 0; > > void *addr = NULL; > > - char buf[MAX_EVENT_NAME_LEN]; > > - char gbuf[MAX_EVENT_NAME_LEN]; > > - char abuf[MAX_BTF_ARGS_LEN]; > > - char *dbuf __free(kfree) = NULL; > > + char *tmp = NULL; > > + long offset = 0; > > > > switch (argv[0][0]) { > > case 'r': > > @@ -893,6 +893,8 @@ static int trace_kprobe_create_internal(int argc, const char *argv[], > > event++; > > > > if (isdigit(argv[0][1])) { > > + char *buf __free(kfree) = NULL; > > So this gets freed when this if block ends, right? Yes, because in this block, "buf" is used as a really temporary buffer. > > > + > > if (!is_return) { > > trace_probe_log_err(1, BAD_MAXACT_TYPE); > > return -EINVAL; > > @@ -905,7 +907,7 @@ static int trace_kprobe_create_internal(int argc, const char *argv[], > > trace_probe_log_err(1, BAD_MAXACT); > > return -EINVAL; > > } > > - memcpy(buf, &argv[0][1], len); > > + buf = kmemdup(&argv[0][1], len + 1, GFP_KERNEL); > > buf[len] = '\0'; > > ret = kstrtouint(buf, 0, &maxactive); > > if (ret || !maxactive) { > > @@ -973,6 +975,9 @@ static int trace_kprobe_create_internal(int argc, const char *argv[], > > > > trace_probe_log_set_index(0); > > if (event) { > > + gbuf = kmalloc(MAX_EVENT_NAME_LEN, GFP_KERNEL); > > + if (!gbuf) > > + return -ENOMEM; > > ret = traceprobe_parse_event_name(&event, &group, gbuf, > > event - argv[0]); > > And you can't use the same trick here because > traceprobe_parse_event_name() assigns "group" to gbuf and is used > outside this if block. Yes, that holds the group name used until parsing the probe. > > I notice there's no comment that states this. At the very minimum, > traceprobe_parse_event_name() should have a kerneldoc comment above its > definition and state this. Yeah, that function should be docummented, it is a bit complicated. > But that's not an issue with this patch > series. Just an observation. Thus... > > Reviewed-by: Steven Rostedt (Google) Thank you! > > -- Steve > > > > if (ret) > > @@ -981,16 +986,22 @@ static int trace_kprobe_create_internal(int argc, const char *argv[], > > > > if (!event) { > > /* Make a new event name */ > > + ebuf = kmalloc(MAX_EVENT_NAME_LEN, GFP_KERNEL); > > + if (!ebuf) > > + return -ENOMEM; > > if (symbol) > > - snprintf(buf, MAX_EVENT_NAME_LEN, "%c_%s_%ld", > > + snprintf(ebuf, MAX_EVENT_NAME_LEN, "%c_%s_%ld", > > is_return ? 'r' : 'p', symbol, offset); > > else > > - snprintf(buf, MAX_EVENT_NAME_LEN, "%c_0x%p", > > + snprintf(ebuf, MAX_EVENT_NAME_LEN, "%c_0x%p", > > is_return ? 'r' : 'p', addr); > > - sanitize_event_name(buf); > > - event = buf; > > + sanitize_event_name(ebuf); > > + event = ebuf; > > } > > > > + abuf = kmalloc(MAX_BTF_ARGS_LEN, GFP_KERNEL); > > + if (!abuf) > > + return -ENOMEM; > > argc -= 2; argv += 2; > > ctx->funcname = symbol; > > new_argv = traceprobe_expand_meta_args(argc, argv, &new_argc, > -- Masami Hiramatsu (Google)