From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-184.mta0.migadu.com (out-184.mta0.migadu.com [91.218.175.184]) (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 AF93F2940B for ; Thu, 18 Sep 2025 11:18:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.184 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758194283; cv=none; b=Bk1r5mTamuwbE29mKhahr2dJlq+WpDPsI9DIgVlLsEwIpND7p/F0u3NidiecWv9WlMzGwcWxCosenqE0jMo/F9oBTP16kx39KEMv8uDjBmsoP3KMSqTVeEObTofrbZKHHPForEMUKJsEASOsVN6WWiXVgFjD7lVgBR2W36NZUkc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758194283; c=relaxed/simple; bh=LCcC386iayVF7Lf5/meg6Ya5puUCR8PvXWTPl4T7+JI=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=BGHZ8RZtOvYbK2q4mMQMmiu28hJk0VQPOA6cP7W3C2myj0M3E86DDY3HlTz9EpOq41s/Yqe5U2I3TQ3vT4oJAVYjVnMpEmtklV1aqZhXYwjK5hBOzSRAWotpzrbcCa86ppHqS4oYUjt2pWGMovOal6P6fgT7DBuFHfwskM8R6Qs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=tW+tHfab; arc=none smtp.client-ip=91.218.175.184 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="tW+tHfab" Message-ID: <63eae916-a404-4fae-b870-203b7e376363@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1758194269; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Y4OFedFFNeXU0WU9ck/G/uCK0A/60b5qhANqkwW6ZQg=; b=tW+tHfabVK0YQcY995tTi9c0umnMIcH/Yq2xOC4Mh4V3I5s6g7RYl6zkqZqEDbzhoFYwvt okrlwfw7h0Tg1or5/Kdt87ZEvbwTIKx2kQnHXXzjBR7A62pM2CjMZymbQH3jfj3YAvPygd uxXQHgHk1DBkLr+0i23xoVjGSvDEI98= Date: Thu, 18 Sep 2025 19:17:32 +0800 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH bpf-next v2 2/2] bpftool: Fix UAF in get_delegate_value To: Quentin Monnet , ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev, eddyz87@gmail.com, song@kernel.org, yonghong.song@linux.dev, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@fomichev.me, haoluo@google.com, jolsa@kernel.org Cc: bpf@vger.kernel.org, linux-kernel@vger.kernel.org References: <20250917034732.1185429-1-chen.dylane@linux.dev> <20250917034732.1185429-2-chen.dylane@linux.dev> <523d8d6c-de99-435f-a01b-1bac72810d53@kernel.org> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Tao Chen In-Reply-To: <523d8d6c-de99-435f-a01b-1bac72810d53@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT 在 2025/9/18 00:30, Quentin Monnet 写道: > 2025-09-17 11:47 UTC+0800 ~ Tao Chen >> The return value ret pointer is pointing opts_copy, but opts_copy >> gets freed in get_delegate_value before return, fix this by free >> the mntent->mnt_opts strdup memory after show delegate value. >> >> Fixes: 2d812311c2b2 ("bpftool: Add bpf_token show") >> Signed-off-by: Tao Chen >> --- >> tools/bpf/bpftool/token.c | 75 +++++++++++++++++---------------------- >> 1 file changed, 33 insertions(+), 42 deletions(-) >> >> diff --git a/tools/bpf/bpftool/token.c b/tools/bpf/bpftool/token.c >> index 82b829e44c8..05bc76c7276 100644 >> --- a/tools/bpf/bpftool/token.c >> +++ b/tools/bpf/bpftool/token.c >> @@ -28,15 +28,14 @@ static bool has_delegate_options(const char *mnt_ops) >> strstr(mnt_ops, "delegate_attachs"); >> } >> >> -static char *get_delegate_value(const char *opts, const char *key) >> +static char *get_delegate_value(char *opts, const char *key) >> { >> char *token, *rest, *ret = NULL; >> - char *opts_copy = strdup(opts); >> >> - if (!opts_copy) >> + if (!opts) >> return NULL; >> >> - for (token = strtok_r(opts_copy, ",", &rest); token; >> + for (token = strtok_r(opts, ",", &rest); token; >> token = strtok_r(NULL, ",", &rest)) { >> if (strncmp(token, key, strlen(key)) == 0 && >> token[strlen(key)] == '=') { >> @@ -44,24 +43,19 @@ static char *get_delegate_value(const char *opts, const char *key) >> break; >> } >> } >> - free(opts_copy); >> >> return ret; >> } >> >> -static void print_items_per_line(const char *input, int items_per_line) >> +static void print_items_per_line(char *input, int items_per_line) >> { >> - char *str, *rest, *strs; >> + char *str, *rest; >> int cnt = 0; >> >> if (!input) >> return; >> >> - strs = strdup(input); >> - if (!strs) >> - return; >> - >> - for (str = strtok_r(strs, ":", &rest); str; >> + for (str = strtok_r(input, ":", &rest); str; >> str = strtok_r(NULL, ":", &rest)) { >> if (cnt % items_per_line == 0) >> printf("\n\t "); >> @@ -69,38 +63,39 @@ static void print_items_per_line(const char *input, int items_per_line) >> printf("%-20s", str); >> cnt++; >> } >> - >> - free(strs); >> } >> >> +#define PRINT_DELEGATE_OPT(opt_name) do { \ >> + char *opts, *value; \ >> + opts = strdup(mntent->mnt_opts); \ >> + value = get_delegate_value(opts, opt_name); \ >> + print_items_per_line(value, ITEMS_PER_LINE); \ >> + free(opts); \ >> +} while (0) > > > Thanks! The fix looks OK to me, but why do you need to have > PRINT_DELEGATE_OPT*() as macros? Can't you just use functions instead? > > Quentin Well, actually, there is no special purpose about using macros, i will use functions as you and Andrri suggested, thanks. -- Best Regards Tao Chen