lkdtm/bugs: Check for the NULL pointer after calling kmalloc

[ Upstream commit 4a9800c81d2f34afb66b4b42e0330ae8298019a2 ]

As the possible failure of the kmalloc(), the not_checked and checked
could be NULL pointer.
Therefore, it should be better to check it in order to avoid the
dereference of the NULL pointer.
Also, we need to kfree the 'not_checked' and 'checked' to avoid
the memory leak if fails.
And since it is just a test, it may directly return without error
number.

Fixes: ae2e1aad3e48 ("drivers/misc/lkdtm/bugs.c: add arithmetic overflow and array bounds checks")
Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
Acked-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220120092936.1874264-1-jiasheng@iscas.ac.cn
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/misc/lkdtm/bugs.c b/drivers/misc/lkdtm/bugs.c
index a337f97b30e28c73c824c8c7d5e6f4fb96bfd51c..d39b8139b0961bb4e99fb9984b55a46a4025397c 100644 (file)
--- a/drivers/misc/lkdtm/bugs.c
+++ b/drivers/misc/lkdtm/bugs.c
@@ -231,6 +231,11 @@ void lkdtm_ARRAY_BOUNDS(void)
 
        not_checked = kmalloc(sizeof(*not_checked) * 2, GFP_KERNEL);
        checked = kmalloc(sizeof(*checked) * 2, GFP_KERNEL);
+       if (!not_checked || !checked) {
+               kfree(not_checked);
+               kfree(checked);
+               return;
+       }
 
        pr_info("Array access within bounds ...\n");
        /* For both, touch all bytes in the actual member size. */