[PATCH v2 13/16] mm/debug_vm_pgtable: Remove uninitialized_var() usage

Kees Cook
2020-06-20T03:31:26Z

Using uninitialized_var() is dangerous as it papers over real bugs[1]
(or can in the future), and suppresses unrelated compiler warnings (e.g.
"unused variable"). If the compiler thinks it is uninitialized, either
simply initialize the variable or make compiler changes. As a precursor
to removing[2] this[3] macro[4], just initialize this variable to NULL.

[1] https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/
[2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/
[3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/
[4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/

Fixes: 399145f9eb6c ("mm/debug: add tests validating architecture page table helpers")
Signed-off-by: Kees Cook <keescook@chromium.org>
---
mm/debug_vm_pgtable.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
index e45623016aea..83c9e88a052a 100644
--- a/mm/debug_vm_pgtable.c
+++ b/mm/debug_vm_pgtable.c
@@ -307,7 +307,7 @@ static int __init debug_vm_pgtable(void)
phys_addr_t paddr;
unsigned long vaddr, pte_aligned, pmd_aligned;
unsigned long pud_aligned, p4d_aligned, pgd_aligned;
- spinlock_t *uninitialized_var(ptl);
+ spinlock_t *ptl = NULL;

pr_info("Validating architecture page table helpers\n");
prot = vm_get_page_prot(VMFLAGS);
--
2.25.1