arm64: vdso: don't free unallocated pages

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.

Fixes: 7c1deeeb0130 ("arm64: compat: VDSO setup for compat layer")
Cc: <stable@vger.kernel.org> # 5.3.x-
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
index 354b11e27c07af0ea52787ad6dfcde6f9e3aa9fa..033a48f30dbb801a58dfe64998fe102eb663aecc 100644 (file)
--- 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)