From: Andrey Zhizhikin <andrey.z@xxxxxxxxx> [ 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@xxxxxxxxxxxxxxxxxxxx> Reviewed-by: Petr Mladek <pmladek@xxxxxxxx> Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx> Cc: Alexei Starovoitov <ast@xxxxxxxxxx> Cc: Andrii Nakryiko <andriin@xxxxxx> Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx> Cc: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx> Cc: Martin KaFai Lau <kafai@xxxxxx> Cc: Petr Mladek <pmladek@xxxxxxxx> Cc: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx> Cc: Song Liu <songliubraving@xxxxxx> Cc: Yonghong Song <yhs@xxxxxx> Cc: bpf@xxxxxxxxxxxxxxx Cc: netdev@xxxxxxxxxxxxxxx Link: http://lore.kernel.org/lkml/20191211080109.18765-1-andrey.zhizhikin@xxxxxxxxxxxxxxxxxxxx Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- 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 b24afc0e6e81c..45b50b89009aa 100644 --- a/tools/lib/api/fs/fs.c +++ b/tools/lib/api/fs/fs.c @@ -210,6 +210,7 @@ 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"); @@ -219,7 +220,8 @@ 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
