From: "Luis R. Rodriguez" <mcgrof@xxxxxxxxxx> Subject: lib/test_kmod.c: fix limit check on number of test devices created As reported by Dan the parentheses is in the wrong place, and since unlikely() call returns either 0 or 1 it's never less than zero. The second issue is that signed integer overflows like "INT_MAX + 1" are undefined behavior. Since num_test_devs represents the number of devices, we want to stop prior to hitting the max, and not rely on the wrap arround at all. So just cap at num_test_devs + 1, prior to assigning a new device. Link: http://lkml.kernel.org/r/20180224030046.24238-1-mcgrof@xxxxxxxxxx Fixes: d9c6a72d6fa2 ("kmod: add test driver to stress test the module loader") Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx> Signed-off-by: Luis R. Rodriguez <mcgrof@xxxxxxxxxx> Acked-by: Kees Cook <keescook@xxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- lib/test_kmod.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff -puN lib/test_kmod.c~test_kmod-fix-limit-check-on-number-of-test-devices-created lib/test_kmod.c --- a/lib/test_kmod.c~test_kmod-fix-limit-check-on-number-of-test-devices-created +++ a/lib/test_kmod.c @@ -1141,7 +1141,7 @@ static struct kmod_test_device *register mutex_lock(®_dev_mutex); /* int should suffice for number of devices, test for wrap */ - if (unlikely(num_test_devs + 1) < 0) { + if (num_test_devs + 1 == INT_MAX) { pr_err("reached limit of number of test devices\n"); goto out; } _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
