Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Andrey Zhizhikin <andrey.zhizhikin@leica-geosystems.com>,
        Petr Mladek <pmladek@suse.com>, Jiri Olsa <jolsa@kernel.org>,
        Alexei Starovoitov <ast@kernel.org>,
        Andrii Nakryiko <andriin@fb.com>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Kefeng Wang <wangkefeng.wang@huawei.com>,
        Martin KaFai Lau <kafai@fb.com>,
        Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
        Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
        bpf@vger.kernel.org, netdev@vger.kernel.org,
        Arnaldo Carvalho de Melo <acme@redhat.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.4 051/113] tools lib api fs: Fix gcc9 stringop-truncation compilation error
Date:   Thu, 27 Feb 2020 14:36:07 +0100
Message-Id: <20200227132219.917375247@linuxfoundation.org>
In-Reply-To: <20200227132211.791484803@linuxfoundation.org>
References: <20200227132211.791484803@linuxfoundation.org>
User-Agent: quilt/0.66
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

From: Andrey Zhizhikin <andrey.z@gmail.com>

[ Upstream commit 6794200fa3c9c3e6759dae099145f23e4310f4f7 ]

GCC9 introduced string hardening mechanisms, which exhibits the error
during fs api compilation:

error: '__builtin_strncpy' specified bound 4096 equals destination size
[-Werror=stringop-truncation]

This comes when the length of copy passed to strncpy is is equal to
destination size, which could potentially lead to buffer overflow.

There is a need to mitigate this potential issue by limiting the size of
destination by 1 and explicitly terminate the destination with NULL.

Signed-off-by: Andrey Zhizhikin <andrey.zhizhikin@leica-geosystems.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andriin@fb.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Yonghong Song <yhs@fb.com>
Cc: bpf@vger.kernel.org
Cc: netdev@vger.kernel.org
Link: http://lore.kernel.org/lkml/20191211080109.18765-1-andrey.zhizhikin@leica-geosystems.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 tools/lib/api/fs/fs.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tools/lib/api/fs/fs.c b/tools/lib/api/fs/fs.c
index 459599d1b6c41..58f05748dd39e 100644
--- a/tools/lib/api/fs/fs.c
+++ b/tools/lib/api/fs/fs.c
@@ -179,6 +179,7 @@ static bool fs__env_override(struct fs *fs)
 	size_t name_len = strlen(fs->name);
 	/* name + "_PATH" + '\0' */
 	char upper_name[name_len + 5 + 1];
+
 	memcpy(upper_name, fs->name, name_len);
 	mem_toupper(upper_name, name_len);
 	strcpy(&upper_name[name_len], "_PATH");
@@ -188,7 +189,8 @@ static bool fs__env_override(struct fs *fs)
 		return false;
 
 	fs->found = true;
-	strncpy(fs->path, override_path, sizeof(fs->path));
+	strncpy(fs->path, override_path, sizeof(fs->path) - 1);
+	fs->path[sizeof(fs->path) - 1] = '\0';
 	return true;
 }
 
-- 
2.20.1