From: Ivan Khoronzhuk <ivan.khoronzhuk@xxxxxxxxxx> [ Upstream commit c588146378962786ddeec817f7736a53298a7b01 ] The "path" buf is supposed to contain path + printf msg up to 24 bytes. It will be cut anyway, but compiler generates truncation warns like: " samples/bpf/../../tools/testing/selftests/bpf/cgroup_helpers.c: In function ‘setup_cgroup_environment’: samples/bpf/../../tools/testing/selftests/bpf/cgroup_helpers.c:52:34: warning: ‘/cgroup.controllers’ directive output may be truncated writing 19 bytes into a region of size between 1 and 4097 [-Wformat-truncation=] snprintf(path, sizeof(path), "%s/cgroup.controllers", cgroup_path); ^~~~~~~~~~~~~~~~~~~ samples/bpf/../../tools/testing/selftests/bpf/cgroup_helpers.c:52:2: note: ‘snprintf’ output between 20 and 4116 bytes into a destination of size 4097 snprintf(path, sizeof(path), "%s/cgroup.controllers", cgroup_path); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ samples/bpf/../../tools/testing/selftests/bpf/cgroup_helpers.c:72:34: warning: ‘/cgroup.subtree_control’ directive output may be truncated writing 23 bytes into a region of size between 1 and 4097 [-Wformat-truncation=] snprintf(path, sizeof(path), "%s/cgroup.subtree_control", ^~~~~~~~~~~~~~~~~~~~~~~ cgroup_path); samples/bpf/../../tools/testing/selftests/bpf/cgroup_helpers.c:72:2: note: ‘snprintf’ output between 24 and 4120 bytes into a destination of size 4097 snprintf(path, sizeof(path), "%s/cgroup.subtree_control", cgroup_path); " In order to avoid warns, lets decrease buf size for cgroup workdir on 24 bytes with assumption to include also "/cgroup.subtree_control" to the address. The cut will never happen anyway. Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@xxxxxxxxxx> Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx> Acked-by: Song Liu <songliubraving@xxxxxx> Link: https://lore.kernel.org/bpf/20191002120404.26962-3-ivan.khoronzhuk@xxxxxxxxxx Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- tools/testing/selftests/bpf/cgroup_helpers.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/testing/selftests/bpf/cgroup_helpers.c b/tools/testing/selftests/bpf/cgroup_helpers.c index e95c33e333a40..b29a73fe64dbc 100644 --- a/tools/testing/selftests/bpf/cgroup_helpers.c +++ b/tools/testing/selftests/bpf/cgroup_helpers.c @@ -98,7 +98,7 @@ int enable_all_controllers(char *cgroup_path) */ int setup_cgroup_environment(void) { - char cgroup_workdir[PATH_MAX + 1]; + char cgroup_workdir[PATH_MAX - 24]; format_cgroup_path(cgroup_workdir, ""); -- 2.20.1
