From 57428298b5acf2ba2dd98359c532774f6eaeecb3 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Tue, 23 Nov 2021 16:23:23 -0800 Subject: [PATCH] selftests/bpf: Prevent out-of-bounds stack access in test_bpffs Buf can be not zero-terminated leading to strstr() to access data beyond the intended buf[] array. Fix by forcing zero termination. Signed-off-by: Andrii Nakryiko Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20211124002325.1737739-12-andrii@kernel.org --- tools/testing/selftests/bpf/prog_tests/test_bpffs.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/bpf/prog_tests/test_bpffs.c b/tools/testing/selftests/bpf/prog_tests/test_bpffs.c index ada95bfb9b1b..214d9f4a94a5 100644 --- a/tools/testing/selftests/bpf/prog_tests/test_bpffs.c +++ b/tools/testing/selftests/bpf/prog_tests/test_bpffs.c @@ -19,11 +19,13 @@ static int read_iter(char *file) fd = open(file, 0); if (fd < 0) return -1; - while ((len = read(fd, buf, sizeof(buf))) > 0) + while ((len = read(fd, buf, sizeof(buf))) > 0) { + buf[sizeof(buf) - 1] = '\0'; if (strstr(buf, "iter")) { close(fd); return 0; } + } close(fd); return -1; } -- 2.50.1