From: Ivan Khoronzhuk ivan.khoronzhuk@linaro.org

[ 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@linaro.org Signed-off-by: Daniel Borkmann daniel@iogearbox.net Acked-by: Song Liu songliubraving@fb.com Link: https://lore.kernel.org/bpf/20191002120404.26962-3-ivan.khoronzhuk@linaro.or... Signed-off-by: Sasha Levin sashal@kernel.org --- 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 cf16948aad4ad..6af24f9a780de 100644 --- a/tools/testing/selftests/bpf/cgroup_helpers.c +++ b/tools/testing/selftests/bpf/cgroup_helpers.c @@ -44,7 +44,7 @@ */ int setup_cgroup_environment(void) { - char cgroup_workdir[PATH_MAX + 1]; + char cgroup_workdir[PATH_MAX - 24];

format_cgroup_path(cgroup_workdir, "");