[PATCH 1/5] arm64: vdso: don't free unallocated pages

Mark Rutland
2020-04-14T10:43:14Z

The aarch32_vdso_pages[] array never has entries allocated in the C_VVAR
or C_VDSO slots, and as the array is zero initialized these contain
NULL.

However in __aarch32_alloc_vdso_pages() when
aarch32_alloc_kuser_vdso_page() fails we attempt to free the page whose
struct page is at NULL, which is obviously nonsensical.

This patch removes the erroneous page freeing.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: stable@vger.kernel.org
---
arch/arm64/kernel/vdso.c | 13 +------------
1 file changed, 1 insertion(+), 12 deletions(-)

diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
index 354b11e27c07..033a48f30dbb 100644
--- a/arch/arm64/kernel/vdso.c
+++ b/arch/arm64/kernel/vdso.c
@@ -260,18 +260,7 @@ static int __aarch32_alloc_vdso_pages(void)
if (ret)
return ret;

- ret = aarch32_alloc_kuser_vdso_page();
- if (ret) {
- unsigned long c_vvar =
- (unsigned long)page_to_virt(aarch32_vdso_pages[C_VVAR]);
- unsigned long c_vdso =
- (unsigned long)page_to_virt(aarch32_vdso_pages[C_VDSO]);
-
- free_page(c_vvar);
- free_page(c_vdso);
- }
-
- return ret;
+ return aarch32_alloc_kuser_vdso_page();
}
#else
static int __aarch32_alloc_vdso_pages(void)
--
2.11.0